February 2000
NSF 00/09/EPADW395
Environmental Technology
Verification Report
Physical Removal of Cryptosporidium
oocysts and Giardia cysts in Drinking
Water
Pall Corporation
WPM-1 Microfiltration Pilot System
Pittsburgh, PA
Prepared by
NSF Internationa!
Under a Cooperative Agreement with
A EPA U.S. Environmental Protection Agency
etVElVElV
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
oEPA
PROGRAM ^
ET V
U.S. Environmental Protection Agency NSF International
ETV Joint Verification Statement
TECHNOLOGY TYPE:
MEMBRANE FILTRATION USED IN PACKAGED
DRINKING WATER TREATMENT SYSTEMS
APPLICATION:
GIARDIA AND CRYPTOSPORIDIUM REMOVAL
TECHNOLOGY NAME:
WPM-1 MICROFILTRATION SYSTEM
TEST LOCATION:
PITTSBURGH, PA
COMPANY:
PALL CORPORATION
ADDRESS:
2200 NORTHERN BLVD
PHONE: (516)484-5400
EAST HILLS, NY 11548
FAX: (516) 484-3216
WEB SITE:
http:Wwww.pall.com
EMAIL:
tom_poschmann@pall.com
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification (ETV) Program to facilitate the deployment of innovative or improved environmental
technologies through performance verification and dissemination of information. The goal of the ETV
program is to further environmental protection by substantially accelerating the acceptance and use of
improved and more cost-effective technologies. ETV seeks to achieve this goal by providing high
quality, peer reviewed data on technology performance to those involved in the design, distribution,
permitting, purchase, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations; stakeholders groups which
consist of buyers, vendor organizations, and permitters; and with the full participation of individual
technology developers. The program evaluates the performance of innovative technologies by developing
test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests (as
appropriate), collecting and analyzing data, and preparing peer reviewed reports. All evaluations are
conducted in accordance with rigorous quality assurance protocols to ensure that data of known and
adequate quality are generated and that the results are defensible.
NSF International (NSF) in cooperation with the EPA operates the Package Drinking Water Treatment
Systems (PDWTS) program, one of 12 technology areas under ETV. The PDWTS program recently
evaluated the performance of a membrane filtration system used in package drinking water treatment
system applications. This verification statement provides a summary of the test results for the Pall
Corporation WPM-1 Microfiltration System. Gannett Fleming, Inc., an NSF-qualified field testing
organization (FTO), performed the verification testing.
00/09/EPADW395 The accompanying notice is an integral part of this verification statement. February 2000
VS-i
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ABSTRACT
Verification testing of the Pall Corporation WPM-1 Microfiltration Pilot System was conducted from
February 3 to March 5, 1999. The treatment system underwent microbial challenge testing on February 5,
1999, and demonstrated a 5.8 logio removal of Giardia cysts and a 6.8 logio removal of Cryptosporidium
oocysts. Source water characteristics were: turbidity average 0.10 Nephlometric Turbidity Units (NTU),
pH 7.7, and temperature 3.6°C. During the thirty-day verification test, the system was operated at a flux
recommended by the manufacturer of 77 gallons per square foot per day (gfd) at 3.8°C which equates to
120 gfd at 20 °C. The average transmembrane pressure was 24 pounds per square inch (psi). The feed
water recovery of the treatment system during the study was 96%. Chemical cleaning of the treatment
system was conducted as part of the verification testing.
TECHNOLOGY DESCRIPTION
Microfiltration (MF) processes are generally used to remove microbial contaminants such as Giardia and
Cryptosporidium and other particulate contaminants from drinking water. The Pall WPM-1 membrane is
a hollow fiber type microfiltration membrane made of polyvinylidenefluoride (PVDF). It has a 0.1
micrometer ((.un) nominal pore size and utilizes outside-in flow. Water is applied under pressure to the
outside of the hollow fiber membrane. The membrane consists of a thin film acting as a sieve. The
membrane is a mechanical barrier, providing removal of particulate contaminants. Permeate (filtered
water) is collected from the inside of the fiber and carried to the permeate outlet.
The Pall Corporation WPM-1 MF Pilot System is a skid mounted, stand alone system. The only required
connections are for the water supply, electrical service, and a sewer connection for the discharge of
backwash and chemical cleaning wastes. The treatment system consists of one membrane module, supply
pump, backwash reservoir and pump, chemical cleaning equipment and necessary gauges and controls.
The unit is equipped with a 400 |_im bag type prefilter to remove large debris from the feed water prior to
introduction to the membranes. The treatment system is capable of operating in an automatic mode with
limited operator intervention.
For this test program, an Excess Recirculation (XR) flow configuration was used. XR flow utilizes water,
which flows tangentially across the upstream side of the filter membrane. To maintain stable flow over
the short term, a backwash cycle called a Reverse Filtration (RF) cycle was performed. At a preset time
determined by raw water quality, the treatment system was backwashed. This was accomplished by
reversing the flow direction; forcing the permeate back through the fibers from inside to outside. (The
permeate was chlorinated using a small diaphragm pump which added sodium hypochlorite to the
permeate prior to backwash.) Every other backwash included an air scrub (AS) to agitate the surface of
the membrane and improve the removal of the particulate material.
VERIFICATION TESTING DESCRIPTION
Test Site
The verification testing site was the Pittsburgh Water and Sewer Authority's (PWSA's) open air Highland
Reservoir No. 1, Pittsburgh, Pennsylvania. The source water for the verification testing was treated
surface water drawn from the Allegheny River. It underwent coagulation, sedimentation, filtration, and
disinfection at PWSA's Aspinwall Treatment Plant prior to being pumped to the Highland Reservoir No.
1. The influent to the treatment unit was drawn from the reservoir effluent lines. The verification testing
was limited to the performance of the equipment to remove Cryptosporidium oocysts and Giardia cysts,
because the source water was obtained from an open reservoir.
00/09/EPADW395 The accompanying notice is an integral part of this verification statement. February 2000
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Methods and Procedures
All field analyses (i.e. pH, turbidity, chlorine residual, temperature) were conducted daily using portable
field equipment according to Standard Methods for the Examination of Water and Waste Water, 18th Ed.,
(APHA, et. al., 1992). Likewise, Standard Methods, 18th Ed., (APHA, 1992) and Methods for Chemical
Analysis of Water and Wastes (EPA, 1979) were used for analyses conducted in PWSA's laboratory.
These analyses included total alkalinity, total hardness, total organic carbon (TOC), dissolved organic
carbon (DOC), total dissolved solids (TDS), total suspended solids (TSS), algae (number and species),
Ultraviolet Absorbance at 254 nanometers (UVA254), total coliform, and heterotrophic plate counts
(HPC). Total alkalinity, total hardness and TDS analyses were conducted monthly. All other laboratory
parameters were analyzed weekly.
Microbial challenge was performed using Giardia cysts and Cryptosporidium oocysts. Procedures
developed by EPA for use during the Information Collection Rule (ICR) were employed for the
identification and enumeration of Giardia cysts and Cryptosporidium oocysts (EPA, ICR Microbial
Laboratory Manual, EPA, April 1996). The protozoans were added to a fifty (50) gallon (190 liter) drum.
This drum was filled with the feed water. A total of 10,768,000 Giardia cysts and 104,548,000
Cryptosporidium oocysts were added to the feed water reservoir. The turbidity of the feed water was 0.10
NTU during the microbial removal challenge testing. This stock suspension was constantly mixed using
a drum mixer. A diaphragm pump was used to add the protozoans to the membranes on the pilot unit.
The pump was operated at about 0.85 gallons per minute (gpm) (3.2 liter per minute) and was capable of
overcoming the pressure in the feed water line of the pilot unit. Samples of the permeate were collected
using a polypropylene wound filter with a nominal pore size of 1.0 (.un. One thousand liters (264 gallons)
of permeate water was filtered through the sampling vessel at one gpm (3.8 liter per minute). In addition,
aliquots of the stock suspension were collected and analyzed to calculate concentrations of the microbes
in the feed water. Backwash was delayed until the end of the collection period. Samples of the backwash
were collected and analyzed to verify that the parasites were added to the system and removed by the
filters.
VERIFICATION OF PERFORMANCE
System Operation
The treatment system was fully automated and capable of normal operations without manual intervention.
The unit automatically operates in the filtration and backwash modes. All operational data, flows,
pressures, turbidity, and particle counts are recorded on data logging software. Manual intervention is
required for chemical cleaning and to occasionally refill the tank of sodium hypochlorite used during
backwash.
The system was operated at a flux recommended by the manufacturer of 77 gfd at 3.8°C (120 gfd at
20°C). The flow rate was recorded twice per day and the water temperature was recorded once per day.
The flow rate of the treatment system averaged 4.0 gpm (15 liter per minute) and ranged from 3.9 to 4.0
gpm (15 liter per minute).
The average feed pressure was 30 psi (2.1 bar [b]). The average retentate pressure was 28 psi (1.9 b).
The filtrate pressure was recorded twice per day. The average filtrate pressure was 5.1 psi (0.35 b). The
amount of pressure lost as the water is filtered through the membrane is referred to as transmembrane
pressure (TMP). It is calculated by averaging the feed water pressure and the retentate pressure and
subtracting the filtrate pressure from that average. The average TMP for the system was 24 psi (1.6 b).
For this test program, a RF interval of once every 30 minutes was used. Every other RF cycle, i.e. once
every hour, utilized an AS cycle. The unit used approximately 3.0 gallons of permeate to backwash the
membranes during a RF cycle. AS followed by RF required 6.2 gallons of permeate.
00/09/EPADW395 The accompanying notice is an integral part of this verification statement. February 2000
VS-iii
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The percent water recovery of the treatment system during the study was 96%. This figure was calculated
by comparing the amount of water needed to backwash the membranes to the total amount of water
filtered by the system.
The effectiveness of the chemical cleaning process was measured by the recovery of specific flux and loss
of original specific flux. Chemical cleaning was conducted at the end of the test period as required by the
ETV Protocol for Equipment Verification Testing for Physical Removal of Microbiological and
Particulate Contamination (EPA/NSF April, 1998). Data collected before and after the chemical cleaning
was used to calculate recovery of specific flux and the loss of original specific flux. The chemical
cleaning recovered 73% of the specific flux. Data from when the membranes were placed into service
and just after cleaning was used to calculate the loss of original specific flux. The loss of original specific
flux was 9.0%.
System integrity was demonstrated as required by the ETV protocol. Tests were conducted on an intact
membrane system and on one that had been intentionally compromised. The air pressure hold test
detected a compromised membrane.
Water Quality Results
During the microbial challenge testing that occurred on February 5, 1999, the Pall WPM-1 MF system
demonstrated a 5.8 logi0 removal of Giardia cysts and a 6.8 logi0 removal of Cryptosporidium oocysts.
The logio removals were limited by the amount of the parasites which were present in the stock feed
solution, the percentage of the permeate that could be sampled, and the percent recovery of the analytical
methodology. There were no Giardia cysts or Cryptosporidium oocysts observed in the permeate. During
the microbial challenge testing, the feed water characteristics were: turbidity average 0.10 NTU, pH 7.7,
temperature 3.6 °C.
During the thirty-day ETV operation of the Pall WPM-1 system, treatment reductions were seen in HPC,
algae, turbidity, and particle counts. HPC concentrations averaged 11 colony forming units (cfu)/100ml in
the feed water and 4 cfu/lOOml in the permeate. The presence of HPC in the permeate may have been
due to inadequate disinfection of the Tygon tubing used for water sampling and to the lid design of the RF
tank which permitted some environmental contaminants to intrude into the permeate side of the system.
Pall reports that the RF tank has been redesigned with a protective lid. Algae concentrations averaged 19
cells/ml in the feed water and <8 cells/ml in the permeate. The turbidity concentration in the feed water
was 0.088 NTU and 0.026 NTU in the permeate. The Pall WPM-1 reduced feed water particle counts
from an average 120 total counts per ml to an average of 0.54 total counts per ml in the filtrate. Total
coliform reduction could not be demonstrated due to the absence of total coliforms in the feed water and
permeate throughout the test. The following table presents the water quality reductions of the feed water
and filtered water samples collected during the 30 days of operation:
Feed Water Quality / Filtered Water Quality
Pall Corporation WPM-1 Microflltration System
Total Coliforms
HPC
Algae
Turbidity
Particle Counts
(cfu/100 ml)
(cfu/100 ml)
(cells/ml)
(NTU)
(particles/ml)
Average1
0/0
11/4
19/<8
0.088/0.026
120/0.54
Minimum1
0/0
2/0
8/<8
0.060/0.024
—
Maximum1
0/0
22/12
32/<8
0.14/0.032
—
Standard Deviation1
0/0
10/5
9.1/0
0.018/0.0013
—
95% Confidence Interval1
N/A/
(2, 19)/
(11,27)/
(0.083,0.092)/
—
N/A
(0, 8)
N/A
(0.026, 0.026)
1 - Concentration of feed water/concentration of filtered water.
N/A = Not Applicable because standard deviation = 0
— = Statistical measurements on cumulative data not calculated.
Note: Calculated averages for less than results (<) utilize half of the Level of Detection (Gilbert, 1987).
00/09/EPADW395 The accompanying notice is an integral part of this verification statement. February 2000
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Temperature of the feed water during the thirty-day ETV study was fairly stable with a high of 4.5°C, a
low of 3.4°C, and an average of 3.8°C. The membrane pilot unit had little or no effect on total alkalinity,
total hardness, TOC, TDS, and UVA254.
Operation and Maintenance Results
Maintenance requirements on the treatment system did not appear to be significant but were difficult to
quantify due to the short duration of the study. The only interruption of the process occurred due to a
power failure at the pumping station. After power was restored to the pumping station the treatment
system was restarted and placed back into service.
The Operating and Maintenance (O&M) Manual provided by Pall Corporation was available for review
on-site and was referenced occasionally during the testing. Particularly, the manual was consulted during
the cleaning procedure. The manual was well organized and a valuable resource during the testing period.
Original Signed by
E. Timothy Oppelt 3/6/00
E. Timothy Oppelt
Director
National Risk Management Laboratory
Office of Research and Development
United States Environmental Protection Agency
Original Signed by
Tom Bruursema 3/6/00
Tom Bruursema
General Manager
Environmental and Research Services
NSF International
NOTICE: Verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and NSF make no
expressed or implied warranties as to the performance of the technology and do not certify that a
technology will always operate as verified. The end user is solely responsible for complying with
any and all applicable federal, state, and local requirements. Mention of corporate names, trade
names, or commercial products does not constitute endorsement or recommendation for use of
specific products. This report is not a NSF Certification of the specific product mentioned herein.
Availability of Supporting Documents
Copies of the ETV Protocol for Equipment Verification Testing for Physical Removal of
Microbiological and Particulate Contaminants dated April 20, 1998 and revised May 14,
1999, the Verification Statement, and the Verification Report (NSF Report
#00/09/EPADW395) are available from the following sources:
(NOTE: Appendices are not included in the Verification Report. Appendices are
available from NSF upon request.)
Drinking Water Systems ETV Pilot Manager (order hard copy)
NSF International
P.O. Box 130140
Ann Arbor, Michigan 48113-0140
NSF web site: http://www.nsf.org/etv (electronic copy)
EPA web site: http://www.epa.gov/etv (electronic copy)
00/09/EPADW395 The accompanying notice is an integral part of this verification statement. February 2000
VS-v
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February 2000
Environmental Technology Verification Report
Physical Removal of Cryptosporidium oocysts and Giardia cysts in
Drinking Water
Pall Corporation WPM-1 Microfiltration Pilot System
Pittsburgh, PA
Prepared for:
NSF International
Ann Arbor, Michigan 48105
Prepared by:
Gannett Fleming
Harrisburg, PA 17106
Under a cooperative agreement with the U.S. Environmental Protection Agency
Jeffrey Q. Adams, Project Officer
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
The U.S. Environmental Protection Agency (EPA) through its Office of Research and
Development has financially supported and collaborated with NSF International (NSF) under
Cooperative Agreement No. CR 824815. This verification effort was supported by Package
Drinking Water Treatment Systems Pilot operating under the Environmental Technology
Verification (ETV) Program. This document has been peer reviewed and reviewed by NSF and
EPA and recommended for public release.
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Foreword
The following is the final report on an Environmental Technology Verification (ETV) test
performed for the NSF International (NSF) and the United States Environmental Protection
Agency (EPA) by Gannett Fleming, Inc., in cooperation with Pall Corporation. The test was
conducted during February and March 1999 at the New Highland Pump Station, Pittsburgh
Water and Sewer Authority, Pittsburgh, Pennsylvania.
Throughout its history, the EPA has evaluated the effectiveness of innovative technologies to
protect human health and the environment. A new EPA program, the Environmental
Technology Verification Program (ETV) has been instituted to verify the performance of
innovative technical solutions to environmental pollution or human health threats. ETV was
created to substantially accelerate the entrance of new environmental technologies into the
domestic and international marketplace. Verifiable, high quality data on the performance of
new technologies is made available to regulators, developers, consulting engineers, and those in
the public health and environmental protection industries. This encourages more rapid
availability of approaches to better protect the environment.
The EPA has partnered with NSF, an independent, not-for-profit testing and certification
organization dedicated to public health, safety and protection of the environment, to verify
performance of small package drinking water systems that serve small communities under the
Package Drinking Water Treatment Systems (PDWTS) ETV Pilot Project. A goal of verification
testing is to enhance and facilitate the acceptance of small package drinking water treatment
equipment by state drinking water regulatory officials and consulting engineers while reducing
the need for testing of equipment at each location where the equipment's use is contemplated.
NSF will meet this goal by working with manufacturers and NSF-qualified Field Testing
Organizations (FTO) to conduct verification testing under the approved protocols.
The ETV PDWTS is being conducted by NSF with participation of manufacturers, under the
sponsorship of the EPA Office of Research and Development, National Risk Management
Research Laboratory, Water Supply and Water Resources Division, Cincinnati, Ohio. It is
important to note that verification of the equipment does not mean that the equipment is
"certified" by NSF or "accepted" by EPA. Rather, it recognizes that the performance of the
equipment has been determined and verified by these organizations for those conditions tested by
the FTO.
111
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Table of Contents
Section Page
Verification Statement VS-i
Title Page i
Notice ii
Foreword iii
Contents iv
Abbreviations and Acronyms x
Acknowledgements xii
Chapter 1 Introduction 1
1.1 ETV Purpose and Program Operation 1
1.2 Testing Participants and Responsibilities 1
1.2.1 NSF International 2
1.2.2 Gannett Fleming 2
1.2.3 Manufacturer 3
1.2.4 Host and Analytical Laboratory 3
1.2.5 U.S. Environmental Protection Agency 4
1.3 Verification Testing Site 4
1.3.1 Source Water 4
1.3.2 Pilot Effluent Discharge 5
Chapter 2 Equipment Description and Operating Processes 6
2.1 Equipment Description 6
2.1.1 Membrane Characteristics 6
2.1.2 Major Equipment Components 6
2.1.3 Data Plate 9
2.2 Operating Process 9
2.2.1 Feed Water 9
2.2.2 Prefiltration 9
2.2.3 Filtration 9
2.2.4 Backwash/Reverse Flow 10
2.2.5 Chemical Cleaning 11
Chapter 3 Methods and Procedures 13
3.1 Experimental Design 13
3.1.1 Objectives 13
3.1.1.1 Evaluation of Stated Equipment Capabilities 13
3.1.1.2 Evaluation of Equipment Performance Relative to Water Quality
Regulations 13
3.1.1.3 Evaluation of Operational Requirements 14
3.1.1.4 Evaluation of Maintenance Requirements 14
3.1.2 Equipment Characteristics 14
3.2 Water Quality Consideration 14
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Table of Contents, continued
Section Page
3.3 Recording Data 15
3.3.1 Operational Data 15
3.3.2 Water Quality Data 15
3.4 Communications, Logistics and Data Handling Protocol 16
3.4.1 Objectives 16
3.4.2 Procedures 16
3.4.2.1 Log Books 16
3.4.2.2 Photographs 17
3.4.2.3 Chain of Custody 17
3.4.2.4 Inline Measurements 17
3.4.2.5 Spreadsheets 17
3.4.2.6 Statistical Analysis 17
3.5 Recording Statistical Uncertainty 18
3.6 Verification Testing Schedule 18
3.7 Field Operations Procedures 18
3.7.1 Equipment Operations 18
3.7.1.1 Operations Manual 19
3.7.1.2 Analytical Equipment 19
3.7.3 Initial Operations 19
3.7.3.1 Flux 19
3.7.3.2 Transmembrane Pressure 20
3.7.3.3 Backwash (Reverse Filtration) 20
3.7.3.4 Percent Feed Water Recovery 21
3.8 Verification Task Procedures 21
3.8.1 Task 1: Membrane Flux and Operation 21
3.8.1.1 Filtration 22
3.8.1.2 Backwash 22
3.8.1.3 Chemical Cleaning 22
3.8.2 Task 2: Cleaning Efficiency 22
3.8.2.1 Cleaning Procedures 23
3.8.3 Task 3: Finished Water Quality 24
3.8.3.1 Sample Collection and Analysis Procedure 24
3.8.4 Task 4: Determination of Maximum Membrane Pore Size 24
3.8.5 Task 5: Membrane Integrity Testing 25
3.8.5.1 Air pressure Hold Test 25
3.8.5.2 Turbidity Reduction Monitoring 25
3.8.5.3 Particle Count Reduction Monitoring 25
3.8.6 Task 6: Giardia and Cryptosporidium Removal 26
3.8.6.1 Feed Water Stock Preparation 26
3.8.6.2 Sample Collection Procedure 26
3.9 QA/QC Procedures 27
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Table of Contents, continued
Section Page
3.9.1 Daily QA/QC Verification Procedures 27
3.9.1.1 Inline Turbidimeter Flow Rate 27
3.9.1.2 Inline Particle Counter Flow Rate 27
3.9.1.3 Inline Turbidimeter Readout 27
3.9.2 Bi-Weekly QA/QC Verification Procedures 28
3.9.2.1 Inline Flow Meter Clean Out 28
3.9.2.2 Inline Flow Meter Flow Verification 28
3.9.3 Procedures for QA/QC Verifications at the Start of Each Testing Period 28
3.9.3.1 Inline Turbidimeter 28
3.9.3.2 Pressure Gauges / Transmitters 28
3.9.3.3 Tubing 29
3.9.3.4 Inline Particle Counters 29
3.9.4 On-Site Analytical Methods 29
3.9.4.1 pH 29
3.9.4.2 Temperature 30
3.9.4.3 Residual Chlorine Analysis 30
3.9.4.4 Turbidity Analysis 30
3.9.5 Chemical and Biological Samples Shipped Off-Site for Analyses 31
3.9.5.1 Organic Parameters 31
3.9.5.2 Microbiological Parameters 31
3.9.5.3 Inorganic Parameters 31
Chapter 4 Results and Discussion 33
4.1 Introducti on 33
4.2 Initial Operations Period Results 33
4.2.1 Flux 33
4.2.2 Transmembrane Pressure 33
4.2.3 B ackwash Frequency 33
4.3 Verification Testing Results and Discussion 34
4.3.1 Task 1: Membrane Flux and Operation 34
4.3.1.1 Transmembrane Pressure Results 34
4.3.1.2 Specific Flux Results 36
4.3.1.3 Cleaning Episodes 37
4.3.1.4 Percent F eed Water Recovery 37
4.3.2 Task 2: Cleaning Efficiency 37
4.3.2.1 Results of Cleaning Episodes 38
4.3.2.2 Calculation of Recovery of Specific Flux and Loss of Original Specific
Flux 39
4.3.2.3 Discussion of Results 39
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Table of Contents, continued
Section Page
4.3.3 Task 3: Finished Water Quality 40
4.3.3.1 Turbidity Results and Removal 40
4.3.3.2 Particle Count Results and Removal 41
4.3.3.3 Feed and Finished Water Testing Results 45
4.3.3.4 Backwash Wastewater Testing Results 47
4.3.3.5 Total Suspended Solids Mass Balance 48
4.3.4 Task 4: Reporting of Maximum Membrane Pore Size 48
4.3.5 Task 5: Membrane Integrity Testing 48
4.3.5.1 Air Pressure Hold Test Results 49
4.3.5.2 Turbidity Reduction Monitoring 49
4.3.5.3 Particle Count Reduction Monitoring 50
4.3.6 Task 6: Giardia and Cryptosporidium Removal 50
4.3.6.1 Feed Water Concentrations 50
4.3.6.2 Permeate Concentrations 51
4.3.6.3 Backwash Examination 52
4.3.6.4 Operational and Analytical Data Tables 52
4.3.6.5 Discussion of Results 54
4.4 Equipment Characteristics Results 54
4.4.1 Qualitative Factors 54
4.4.1.1 Susceptibility to Changes in Environmental Conditions 54
4.4.1.2 Operational Reliability 55
4.4.1.3 Equipment Safety 55
4.4.2 Quantitative Factors 55
4.4.2.1 Power Supply Requirements 56
4.4.2.2 Consumable Requirements 56
4.4.2.3 Waste Disposal 56
4.4.2.4 Length of Operating Cycle 57
4.5 QA/QC Results 57
4.5.1 Daily QA/QC Results 57
4.5.2 Bi-weekly QA/QC Verification Results 58
4.5.3 Results of QA/QC Verifications at the Start of Each Testing Period 59
4.5.4 Analytical Laboratory QA/QC 60
Chapter 5 References 61
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Table of Contents, continued
Tables Page
Table 1-1 Pall Corporation WPM-1 MF Pilot System Feed Water Quality 5
Table 3-1 Analytical Data Collection Schedule 15
Table 3-2 Operational Data Collection Schedule 15
Table 3-3 Analytical & Operational Data Collection Schedule - Chemical Cleaning 23
Table 4-1 Daily Unit Pressure Readings and Transmembrane Pressure 34
Table 4-2 Specific Flux 36
Table 4-3 Chemical and Physical Characteristics of Cleaning Solution 38
Table 4-4 Operational Parameter Results - Cleaning Procedure 38
Table 4-5 Turbidity Analyses Results and Removal 40
Table 4-6. Filtrate Turbidity Results - Four Hour Readings 40
Table 4-7 Feed Water Particle Counts 42
Table 4-8 Finished Water Particle Counts 42
Table 4-9 Daily Average Cumulative Particle Counts Feed and Finished Water Logio
Particle Removal 43
Table 4-10 Feed Water Testing Results 45
Table 4-11 Finished Water Testing Results 46
Table 4-12 Daily Backwash Wastewater Testing Results - Summary 47
Table 4-13 Weekly Backwash Wastewater Testing Results 48
Table 4-14 Giardia and Cryptosporidium Stock Suspension Results by Hemocytometer
Counts 51
Table 4-15 Giardia and Cryptosporidium Stock Suspension Results by Microscopic
Examination 51
Table 4-16 Giardia and Cryptosporidium Challenge LogioRemoval Calculation 52
Table 4-17 Pressure Readings and Calculations During Giardia and Cryptosporidium
Removal Testing 52
Table 4-18 Specific Flux During Giardia and Cryptosporidium Removal Testing 53
Table 4-19 Turbidity Analyses Results and Removal During Giardia and Cryptosporidium
Removal Testing 53
Table 4-20 Feed Water Particle Counts 2/5/1999 53
Table 4-21 Finished Water Particle Counts 2/5/1999 53
Table 4-22 Daily Backwash Wastewater Testing Results During Giardia and
Cryptosporidium Removal Testing 53
Figures Page
Figure 2-1 Forward Flow Water Production 10
Figure 2-2 Flow Path During Reverse Filtration and Air Scrub 11
Figure 2-3 Chemical Cleaning Procedures and Flow Schematic 12
Figure 4-1 Transmembrane Pressure vs. Time 35
Figure 4-2 Specific Flux Decline vs. Time 36
Figure 4-3 Four-Hour Permeate Turbidity 41
Figure 4-4 Four Hour Feed Water Particle Counts 44
Figure 4-5 Four Hour Permeate Particle Counts 44
Figure 4-6 Daily Average Logio Cumulative Particle Removal Graph 45
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Table of Contents, continued
Photographs
Photograph 1 Pall WPM-1 Microfiltration System
Photograph 2 Side View of the Pall WPM-1 Microfiltration System
Page
8
8
Appendices
A. Laboratory Approval Statements
B. Manufacturer's Operation and Maintenance Manual
C. Data Spreadsheets
D. Data Log Book
E. Laboratory Chain of Custody Forms
F. PWSA Laboratory QA/QC Plan
G. Field Operations Document
H. Laboratory Reports and Challenge Testing Reports and Bench Sheets
I. Manufacturer's Membrane Pore Size Report
J. Particle Counter Information
K. Pilot Plant Photos
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Abbreviations and Acronyms
ac
acres
AS
Air Scrub
A WW A
American Water Works Association
b
bar
CaC03
Calcium Carbonate
CCP
Composite Correction Program
cfu
colony forming unit
CIP
clean in place
Cl2
chlorine
°c
degrees Celsius
DI
deionized
DOC
Dissolved Organic Carbon
EPA
U.S. Environmental Protection Agency
ESWTR
Enhanced Surface Water Treatment Rule
ETV
Environmental Technology Verification
°F
degrees Fahrenheit
FOD
Field Operations Document
ft
feet
ft2
feet squared
FTO
Field Testing Organization
gfd
gallon per square foot per day
gpm
gallon per minute
hp
horse power
HPC
Heterotrophic Plate Count
hr
hour
ICR
Information Collection Rule
in
inch
kD
Kilo Daltons
L
liters
lbs
pounds
l/m2/h
liter per square meter per hour
l/m2/h/b
liter per square meter per hour per bar
1pm
liter per minute
m
meter
MF
Microfiltration
MG
million gallon
MGD
million gallon per day
mg/L
milligram per liter
ml
milliliters
mm
millimeters
MSDS
Material Safety Data Sheets
N/A
Not Applicable
NIST
National Institute of Standards and Technology
x
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NSF
NSF International (formerly known as National Sanitation
Foundation)
nm
nanometers
NTU
Nephlometric Turbidity Units
od
outside diameter
O&M
Operations and Maintenance
PADEP
Pennsylvania Department of Environmental Protection
PC
personal computer
PPE
Personal Protective Equipment
ppm
parts per million
psi
pounds per square inch
psid
pounds per square inch differential
PDWTS
Packaged Drinking Water Treatment System
PVC
Polyvinylchloride
PVDF
Polyvinylidenefluoride
PWSA
Pittsburgh Water and Sewer Authority
QA/QC
Quality Assurance/Quality Control
RF
Reverse Flow
scfm
standard cubic feet per minute
SDI
Silt Density Index
SDWA
Safe Drinking Water Act
SST
stainless steel
SWTR
Surface Water Treatment Rule
TDS
Total Dissolved Solids
TMP
Transmembrane Pressure
TOC
Total Organic Carbon
TSS
Total Suspended Solids
|im
micrometers
uva254
Ultraviolet Absorbance at 254nm
XR
Excess Recirculation
XI
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ACKNOWLEDGMENTS
The Field Testing Organization, Gannett Fleming, Inc., was responsible for all elements in the
testing sequence, including collection of samples, calibration and verification of instruments,
data collection and analysis, data management, data interpretation and the preparation of this
report.
Gannett Fleming, Inc.
P.O. Box 67100
Harrisburg, PA 17106-7100
Phone: 717-763-7211
Contact Person: Mr. Gene Koontz
The laboratory selected for microbiological analysis and non-microbiological, analytical work of
this study was:
Pittsburgh Water and Sewer Authority
900 Freeport Road
Pittsburgh, PA 15238
Phone: 412-782-7552
Contact Person: Mr. Stanley States, Ph.D., Director of Analytical Services
The Manufacturer of the Equipment was:
Pall Corporation
2200 Northern Boulevard
East Hills, NY 11548
Phone: (516) 484-5400
Contact Person: Michelle Frisch, Senior Sales Engineer
Gannett Fleming wishes to thank NSF International, especially Bruce Bartley, Project Manager,
Carol Becker and Kristie Wilhelm, Environmental Engineers, and Tina Beaugrand,
Microbiology Laboratory Auditor for providing guidance and program management.
The Pittsburgh Water and Sewer Authority staff including Dr. Stanley States, Director of
Analytical Services, Raymond Wisloski, Water Treatment Plant Manager, Chester Grassi,
Assistant Plant Manager, and Mickey Schuering, Water Treatment Technician provided
invaluable analytical and operational assistance.
Michelle Frisch, Senior Sales Engineer, Lou Mattera, Senior Project Engineer, Jim Moy, Field
Engineer, and Jen Hays, Senior Test Engineer Pall Corporation are to be commended for
providing the treatment system and excellent technical and product expertise. John and Brian
Regan, President and Vice president for Biltmore Products Company provided assistance during
the pilot setup and tear down as well as assistance during the pilot operation.
Xll
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Chapter 1
Introduction
1.1 ETV Purpose and Program Operation
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification (ETV) Program to facilitate the deployment of innovative or improved
environmental technologies through performance verification and dissemination of information.
The goal of the ETV program is to further environmental protection by substantially accelerating
the acceptance and use of improved and more cost-effective technologies. ETV seeks to achieve
this goal by providing high quality, peer reviewed data on technology performance to those
involved in the design, distribution, permitting, purchase, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations; stakeholders
groups which consist of buyers, vendor organizations, and permitters; and with the full
participation of individual technology developers. The program evaluates the performance of
innovative technologies by developing test plans that are responsive to the needs of stakeholders,
conducting field or laboratory (as appropriate), collecting and analyzing data, and preparing peer
reviewed reports. All evaluations are conducted in accordance with rigorous quality assurance
protocols to ensure that data of known and adequate quality are generated and that the results are
defensible.
NSF International (NSF) in cooperation with the EPA operates the Package Drinking Water
Treatment Systems (PDWTS) program, one of 12 technology areas under ETV. The PDWTS
program evaluated the performance the Pall Corporation WPM-1 Microfiltration (MF) Pilot
System, which is a membrane filtration system used in package drinking water treatment system
applications. The performance claim evaluated during field testing of the Pall WPM-1 MF
System was that the system is capable of a minimum 3 logio removal of Giardia cysts and 2 logio
removal of Cryptosporidium oocysts. This document provides the verification test results for the
Pall WPM-1 MF System.
1.2 Testing Participants and Responsibilities
The ETV testing of the Pall WPM-1 MF System was a cooperative effort between the following
participants:
NSF International
Gannett Fleming, Inc.
Pall Corporation
Pittsburgh Water and Sewer Authority
U.S. Environmental Protection Agency
The following is a brief description of each ETV participant and their roles and responsibilities.
1
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1.2.1 NSF International
NSF is a not-for-profit testing and certification organization dedicated to public health safety and
the protection of the environment. Founded in 1946 and located in Ann Arbor, Michigan, NSF
has been instrumental in the development of consensus standards for the protection of public
health and the environment. NSF also provides testing and certification services to ensure that
products bearing the NSF Name, Logo and/or Mark meet those standards. The EPA partnered
with the NSF to verify the performance of package drinking water treatment systems through the
EPA's ETV Program.
NSF provided technical oversight of the verification testing. An audit of the field analytical and
data gathering and recording procedures was conducted. NSF also provided review of the Field
Operations Document (FOD) and this report.
Contact Information:
NSF International
789 N. Dixboro Rd.
Ann Arbor, MI 48105
Phone: 734-769-8010
Fax: 734-769-0109
Contact: Bruce Bartley, Project Manager
Email: bartley@nsf.org
1.2.2 Gannett Fleming, Inc.
Gannett Fleming, Inc., a consulting engineering firm, conducted the verification testing of the
Pall WPM-1 MF System. Gannett Fleming is a NSF-qualified Field Testing Organization (FTO)
for the Packaged Drinking Water Treatment System ETV pilot project.
The FTO was responsible for conducting the verification testing for 30 calendar days. The FTO
provided all needed logistical support, established a communications network, and scheduled and
coordinated activities of all participants. The FTO was responsible for ensuring that the testing
location and feed water conditions were such that the verification testing could meet its stated
objectives. The FTO prepared the FOD, oversaw the pilot testing, managed, evaluated,
interpreted and reported on the data generated by the testing, as well as evaluated and reported
on the performance of the technology.
FTO employees conducted the onsite analyses and data recording during the testing. Oversight
of the daily tests was provided by the FTO's Project Manager and Project Director.
Contact Information:
Gannett Fleming, Inc.
P.O. Box 67100
Harrisburg, PA 17106-7100
Phone: 717-763-7211
Fax: 717-763-1808
2
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Contact: Gene Koontz, Project Director
Email: gkoontz@gfnet.com
1.2.3 Manufacturer
The treatment system is manufactured by Pall Corporation, a manufacturer of membrane and
microporous, non-woven filtration and separation products to municipal and industrial water
users. Based in East Hills, New York, Pall Corporation has manufacturing facilities located in
the United States, Puerto Rico, England, Ireland, Germany, Holland, Japan, China, and India.
The manufacturer was responsible for supplying a field-ready MF membrane filtration pilot plant
equipped with all necessary components including treatment equipment, instrumentation and
controls and an operations and maintenance manual. The unit was capable of continuous, safe
24 hour per day operation with minimal operator attention. The unit was equipped with
protective devices to provide for automatic shut down of the pilot plant in the event of loss of
feed water or any other condition that would either damage the pilot plant or render data
generated by the unit to be not reliable. The manufacturer was responsible for providing
logistical and technical support as needed as well as providing technical assistance to the FTO
during operation and monitoring of the equipment undergoing field verification testing.
Representatives of the manufacturer assisted in conducting chemical clean in place (CIP),
membrane integrity testing, and examined daily operational data that was automatically recorded
by the treatment system.
Contact Information:
Pall Corporation
2200 Northern Boulevard
East Hills, NY 11548
Phone: (516) 484-5400
Contact Person: Michelle Frisch, Senior Sales Engineer
Email: michelle_sini@pall.com
1.2.4 Host and Analytical Laboratory
The verification testing was hosted by the Pittsburgh Water and Sewer Authority (PWSA).
PWSA serves water to over 500,000 people from its 120 million gallon per day (MGD) surface
water treatment plant located in the Aspinwall section of the City of Pittsburgh. PWSA was
interested in examining the use of membrane filtration to treat water, which had been stored in its
Highland Reservoir No. 1, an open finished water reservoir.
PWSA's laboratory provided collection and analytical services for Total Alkalinity, Total
Hardness, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Total Coliforms,
Heterotrophic Plate Count (HPC), Total Organic Carbon (TOC), Ultraviolet Absorbance at 254
nanometers (UVA254), and Algae. In addition, PWSA supplied operational support and
analytical services for the microbial removal testing. PWSA's laboratory is certified by the
Pennsylvania Department of Environmental Protection (PADEP) for analysis of Microbiological,
3
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Inorganic, and Organic compounds in water. Additionally, the laboratory has received Protozoa
Laboratory Approval from the EPA under the Information Collection Rule (ICR) Program.
Copies of the Laboratory Approval Statements are attached in Appendix A.
Contact Information:
Pittsburgh Water and Sewer Authority
900 Freeport Road
Pittsburgh, PA 15238
Phone: 412-782-7552
Fax: 412-782-7564
Contact: Stanley States, Ph.D. Director of Analytical Services
1.2.5 U.S. Environmental Protection Agency
The EPA through its Office of Research and Development has financially supported and
collaborated with NSF under Cooperative Agreement No. CR 824815. This verification effort
was supported by Package Drinking Water Treatment Systems Pilot operating under the ETV
Program. This document has been peer reviewed and reviewed by NSF and EPA and
recommended for public release.
1.3 Verification Testing Site
The verification testing site was at the PWSA's Highland Reservoir No. 1. The physical location
of the treatment unit was the New Highland Pumping Station at the corner of North Negley
Avenue and Mellon Terrace in the Highland Park section of the City of Pittsburgh, Pennsylvania.
The treatment unit was housed in the pumping station itself and received its feed water from the
influent lines of the pumping station.
1.3.1 Source Water
The source water for the verification testing was finished drinking water that was stored in
PWSA's open Highland Reservoir No. 1. The reservoir is 18 acres (ac) with an average depth of
20 feet (ft) and contains 120 million gallons (MG) of water. The water that is stored in Highland
Reservoir No. 1 is treated surface water drawn from the Allegheny River. The water stored in the
reservoir has undergone coagulation, sedimentation, filtration, and disinfection at PWSA's
Aspinwall Treatment prior to being pumped to the reservoir. The influent to the Pall WPM-1
MF system was drawn from the reservoir effluent lines. The effluent from the reservoir is not
tested by PWSA and the Authority has little historical data regarding the quality of the reservoir
water. The verification testing was limited to the performance of the equipment to remove
Cryptosporidium oocysts and Giardia cysts, because the source water was obtained from an open
reservoir. The performance was evaluated during challenge seeding studies of Cryptosporidium
oocysts and Giardia cysts.
During the thirty-day ETV test period, the feed water turbidity ranged from 0.060 to 0.14
Nephlometric Turbidity Units (NTU) with an average of 0.088 NTU. pH was within the range of
4
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7.6 to 8.0 with an average of 7.8. Total alkalinity as CaCC>3 ranged from 37 to 48 mg/1 with an
average of 42 mg/1. Average hardness, as CaCC>3, was 95 mg/1 and ranged from 84 to 104 mg/1.
TOC ranged from 2.0 to 2.6 mg/1 with an average of 2.3 mg/1. UVA254 was 0.022 mg/1 on
average, with a range of 0.020 to 0.030 mg/1. TDS averaged 200 mg/1 and the range was 170 to
270 mg/1. TSS averaged 0.19 mg/1 and ranged from non-detectable to 0.55 mg/1. No coliform
bacteria were detected in the feed water. The feed water cumulative particle counts averaged 120
counts/ml. Temperature averaged 3.8°C, ranging from 3.4°C to 4.5°C. The alga levels during the
verification testing averaged 19 cell/ml, with a range of 8 to 32 cells/ml. A summary of the feed
water quality information is presented in Table 1-1 below.
Table 1-1. Pall Corporation WPM-1 MF Pilot System Feed Water Quality
Parameter
Total
Total
TDS
TSS
Total
HPC
TOC
UVA Algae
Turbidity
Alkalinity Hardness
Coliforms
(mg/1)
(mg/1)
(mg/1)
(mg/1)
(cfu/100
(cfu/100
(mg/1)
(cm-1) (cells/ml)
(NTU)
ml)
ml)
Average
42
95
200
0.19
0
11
2.3
0.022 19
0.088
Minimum
37
84
170
<0.050
0
2
2.0
0.020 8.0
0.060
Maximum
48
100
270
0.55
0
22
2.6
0.030 32
0.14
Std. Dev.
4.5
7.3
38.9
0.27
0
9.7
0.2
0.0045 9.1
0.018
95% Confid Int
(38,46)
(89, 100)
(170,
(-0.040,
N/A
(2.5,20)
(2.1,2.5)
(0.018, (11,27)
(0.07,0.11)
240)
0.42)
0.026)
N/A = Not Applicable because standard deviation = 0
Note: Calculated averages for less than results (<) utilize half of the Level of Detection (0.05 mg/1) or 0.025 mg/1 in these
calculations. Per Statistical Methods for Environmental Pollution Monitoring. Richard O. Gilbert, Van Nostrand Reinhold, 1987.
1.3.2 Pilot Effluent Discharge
The effluent of the pilot treatment unit was piped to an existing catch basin that is part of the
PWSA sanitary sewer collection system. No discharge permits were required.
5
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Chapter 2
Equipment Description and Operating Processes
2.1 Equipment Description
The equipment tested in this ETV program was Pall Corporation WPM-1 Microfiltration Pilot
System. The modules used in the WPM-1 Treatment System was the Microza USV-3003
module with PVC housing. The PVC housings accommodate bundles of 1800 PVDF hollow
fiber membranes, rated at 0.1 micrometer (|im). The hollow fiber membranes are 1.4 millimeters
(mm) outside diameter and 0.8 mm inside diameter. The fibers contain thousands of micro-pores
from 0.1 to 0.004 |im in diameter. This correlates to a 13,000 Dalton (molecular weight) rating.
The module is vertically mounted on the treatment skid. The filtration surface area provided in a
module is approximately 75 ft2.
The fibers are potted in epoxy, and arranged so that the feed flow enters the bottom of the
module and flows on the outside of the fibers. Water passes into the fiber interior core via the
pores. Contaminates which cannot pass through the pores remain exterior to the filter module.
Water which enters the fibers' hollow interior is conducted into the interior of the filter module
and exits as clean permeate. This 'outside-in' flow path provides for larger effective membrane
area, and allows higher flux rates than most other membranes.
2.1.1 Membrane Characteristics
A summary of membrane characteristics as reported by the manufacturer is as follows:
Membrane classification Microfiltration
Membrane material PVDF
Membrane type hollow fiber
Membrane flow path outside in
Filtration mode Recirculation
pH tolerance 1-10
Temperature tolerance 1 - 35° C (33 - 95° F)
2.1.2 Major Equipment Components
The following major equipment components are provided on the WPM-1 Treatment System:
Modules:
(1) Microza USV-3003 module with PVC housing. These are 1.12 meter
long, 3" diameter PVC housings that accommodate bundles of 1800 PVDF
hollow fibers, rated at 0.1 micron.
Pre-filter:
FSI 304 stainless steel (SST) bag filter housings with 400 micron
polyester mesh bag filters.
6
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Tanks:
Feed Tank:
10 gallon rectangular tank, flat bottom, closed top, SST stand.
Reverse Filtration Tank:
10 gallon rectangular tank, flat bottom, closed top, SST stand.
Chlorine Tank:
15 Liter polyethylene carboy, removable top.
Piping:
General: Sch 80, PVC, socket welded or threaded
Chlorine tubing: 3/8" OD Teflon PVDF
Air piping: 1/4" OD 304 SST tubing.
Pumps:
Feed Pump:
Goulds G&L Type SST/1ST centrifugal, 304 SST, lxl.25-6 EPR
elastomers, carbon/ceramic single mechanical seal, 1.5 horse power
(hp) 3450 RPM, 230-460/60/3 inverter duty TEFC motor, and ABB
ACS-2P1-1 variable frequency drive. Design: ambient temperature
water, 20 GPM @ 100 ft. TDH.
Reverse Filtration Pump:
Goulds G&L Type SST/1ST centrifugal, 304 SST, lxl.25-6, EPR
elastomers, carbon/ceramic single mechanical seal, 1.5 hp 3450 RPM,
230-460/60/3 inverter duty TEFC motor, and ABB ACS-2P1-1
variable frequency drive. Design: ambient temperature water, 20
GPM @ 100 ft. TDH.
Chemical Feed Pump:
Blue - White 15N302I with adjustable stroke, 0.7 - 35 GPD.
Valves:
Asahi, Duo Block True Union PVC w/ EPDM Elastomers
Instrumentation:
Level Switches - SIE SK1-20-M30-P-B-S-Y2
Pressure Transmitters - Setra C207, 0-100 psig, w/865 option (Nema 4
housing).
Temperature Transmitters - Pyromation RTD type. # R1T185L 48 2.5
65 T 401 1 85 1750C-00
Flow meters - Signet - #3-8512 incl 3-8512-PO & #3-8011.
Turbidimeter - Hach 1720C. 44000-10 1720C w/44156-00 Calibration
Kit
Controls:
GE Fanuc Model 331 PLC with Nematron W5000 flat panel computer
running Wonderware Intouch Human Machine Interface software, housed
in a NEMA 4 enclosure.
The following two photographs were taken of the equipment while it was on-site at the PWSA
Highland Reservoir No. 1 location for testing:
7
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Photograph 1. Pall WPM-1 Microfiltration System
On Location at the PWSA Site.
Photograph 2. Side View of the Pall WPM-1 Microfiltration System On Location at the
PWSA Site.
8
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2.1.3 Data Plate
The data plate affixed to the treatment system contains the following information.
a. Equipment name: WPM-1 Pilot System
b. Model #: WPM-1 Pilot System
c. Manufacturer: Pall Corporation, 2200 Northern Boulevard, East Hills, NY 11548
d. Electrical requirements: 208 - 240 VAC, 15Amps, 1 phase
e. Serial number: 2114562
f. Warning and caution statements: N/A
g. Capacity or output rate: 1 -5 gallons per minute (gpm)
2.2 Operating Process
2.2.1 Feed Water
The feed water is pumped into the filtration system by the feed pump. The feed pump provides
the pressure needed to drive the raw water through the fibers.
2.2.2 Prefiltration
A disposal 400|am bag filter removes large particles prior to the feed flow entering the modules.
The prefilter protects the membrane fibers against clogging. The prefilter is visually inspected
regularly. The prefilter is cleaned or replaced during CIP procedures or as indicated by the
visual inspection or as dictated by raw water quality.
2.2.3 Filtration
During normal (forward) flow, the module receives an inlet flow. This flow enters the bottom of
the module, and flows up the module on the outside of the hundreds of hollow fibers that run the
length of the module. Of this, 95% 'permeates' through the fiber surface, travels up the inside of
the hollow fiber, and flows into the Reverse Filtration Tank before leaving the system as clean
water. The remaining five percent is recycled back to the Feed Tank as Excess Recirculation
(XR). This XR flow prevents the accumulation of any gasses that may come out of solution in
the module, and helps to ensure even flow distribution throughout the module. Figure 2-1
illustrates the flow path during forward flow.
9
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Water Processing
MF Systems
Forward Flow Water Production
Feed
it1,? c
I
Excess
Recirculation
Filtrate
^ Module
Pall Corporation Proprietar5
Figure 2-1. Forward Flow Water Production
2.2.4 Backwash/Reverse Filtration
As water is filtered through the membrane surface, a film of rejected particulates accumulates on
the surface of the fibers. With greater accumulation, this gradually impedes the permeate flow.
To maintain stable flow over the short term, a periodic cleaning cycle, called a Reverse Filtration
(RF) Cycle, is performed. RF serves to keep module flux high. It is analogous to "backwashing"
where filter flow is reversed. The reverse flow allows the particles trapped at the membrane to
free the membrane pores and direct their exit from the system. This eliminates the flow
restriction arising from particles plugging membrane pores.
To aid in cleaning the module, and particularly in removing any bio-burden on the membrane
surfaces, chlorine, in the form of 12.5% sodium hypochlorite, is injected into the RF flow stream.
The level of chlorine in the RF feed is approximately 20 mg/L. Valves direct all chlorine-laden
RF-clean flow to waste.
Reverse filtration is not totally effective in cleaning the membrane fibers, and occasionally, a
more vigorous cleaning is required. Pall calls the method Air Scrubbing (AS). This is a two step
process. The first step consists of bubbling about 3 standard cubic feet per minute (scfrn) of
compressed air through each module with no water flow. The air is introduced into the feed
connection of the module. Gaseous air will not pass through the fibers, so this air stays on the
10
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feed side of the membrane. The air bubbles shake the fibers, sloughing off material that resists
the RF cycle.
The second part of the AS cycle serves as a rinse and flush. Air is still bubbled up through the
module, but water is also circulated through the feed side of the module. This is even more
effective in cleaning the module surface. AS is an energetic process. For this reason, the number
of AS cycles must be kept to the minimum required to keep the modules clean. Figure 2-2
illustrates the flow path during RF and AS.
i Mr i ^ i
'»w'ti-.O.*
MF S
Regeneration Methods
Reverse Filtration Air Scrub
Chlorine
Optional
LQk iltrate
Pump
\fmlilh'
To Drain
Air & Water
Out
_c
J—
Air
In
Pall Corporation Proprietar)
Figure 2-2. Flow Path During Reverse Filtration and Air Scrub
2.2.5 Chemical Cleaning
Even AS cycles leave some residue on the module fibers, and must be augmented by occasional
chemical cleaning. In the WPM-1 system, the CIP process requires scheduled down-time and
the entire system must be taken off line for several hours. In new systems, the CEP cycle is
initially scheduled every two to three months. The nature of the foulants affects the cleaning
frequency. As flow or incoming contaminant levels increase, it is likely that the CIP frequency
will increase, accordingly.
11
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The CIP process is done manually on the Pilot Skid (CIP is generally automated for larger,
permanent systems). The system is drained, and then refilled with permeate. Sodium hydroxide
is added to the permeate and circulated through the system for 20 minutes. Then citric acid is
added to the permeate and circulated through the system for 20 minutes. The solution is drained,
and more permeate (or other clean water) is added and circulated to rinse the system. The MF
system is now ready to go back on line. For some applications, sodium hypochlorite can be
substituted for the citric acid.
Figure 2-3 is a schematic representation of the chemical cleaning process.
(pall)
MF System
Two-Step Chemical Cleaning
Citric Acid Step:
a. make up 2% citric acid solution (e.g. 16 |
lbs 100% citric acid in 100 gal 30°C water)
b. recirc. @ 75% flowrate for 20 min
c. do RF (no chlorine during RF!)
d. soak 20 min
e. flush with water until pH is neutral (5-10
min)
Caustic Step:
a. make up a 0.4% NaOH w/ 300 ppm
NaOCI (e.g. 1 gal 40% caustic and 1L 12.5%
hypochlorite in 100 gal 30°C water)
b. recirculate @ 75% flowrate for 20 min
c. do RF
d. soak 20 min
e. flush with water (5-10 min)
CIP
Soluti
Pall Corporation Proprietary
Figure 2-3. Chemical Cleaning Procedure and Flow Schematic
12
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Chapter 3
Methods and Procedures
3.1 Experimental Design
The experimental design of this verification study was developed to provide accurate information
regarding the performance of the treatment system. The impact of field operations as they relate
to data validity was minimized, as much as possible, through the use of standard sampling and
analytical methodology. Due to the unpredictability of environmental conditions and mechanical
equipment performance, this document should not be viewed in the same light as scientific
research conducted in a controlled laboratory setting.
3.1.1 Objectives
The verification testing was undertaken to evaluate the performance of the Pall Corporation
WPM-1 MF Pilot System. Specifically evaluated were the manufacturer's stated equipment
capabilities and equipment performance relative to water quality regulations. Also evaluated
were the operational requirements and maintenance requirements of the system. The details of
each of these evaluations are discussed below.
3.1.1.1 Evaluation of Stated Equipment Capabilities
The Pall WPM-1 Microfiltration treatment unit was tested to show that it was capable of
providing a minimum 3 logio removal of Giardia cysts and 2 logio removal of Cryptosporidium
oocysts from the source water and consistently producing water with a turbidity of less than <0.1
NTU. Giardia and Cryptosporidium removal challenge testing was conducted to demonstrate
acceptable protozoan removal capability. Since turbidity challenge testing was not done during
the course of the study and the turbidity of the feed water was quite low, turbidity removal
capabilities were not verified during the course of the testing.
3.1.1.2 Evaluation of Equipment Performance Relative to Water Quality Regulations
Drinking water regulations require, for filtration plants treating surface water, a minimum of 3
logio removal/inactivation of Giardia cysts from feed to finished waters, that finished water
turbidity at no time exceeds 5 NTU and that at least 95% of the daily finished water turbidity
samples be less than 0.5 NTU. (EPA, Surface Water Treatment Rule [SWTR], 1989). Recently
promulgated rules have modified the SWTR to include a lower turbidity standard, less than 0.3
NTU in 95% of the daily finished water turbidity samples, and a requirement to provide a 2 logio
removal of Cryptosporidium oocysts (EPA, Enhanced Surface Water Treatment Rule [ESWTR],
1999). Both these rules grant the "log removal credit" if the treatment facility achieves the
required turbidity levels.
The treatment system's ability to achieve required finished water turbidity levels was not
verifiable due to the fact that the feed water already was in compliance with drinking water
turbidity regulations. Log removal for Giardia cysts and Cryptosporidium oocysts was
13
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quantified using microbial removal challenge testing although there is no provision for this type
of testing in the regulations.
3.1.1.3 Evaluation of Operational Requirements
An overall evaluation of the operational requirements for the treatment system was undertaken as
part of the verification. This evaluation was qualitative in nature. The manufacturer's
Operations and Maintenance (O&M) manual (Membrane System Operating Manual, Pall
Corporation, February, 1998) and experiences during the daily operation were used to develop a
subjective judgement of the operational requirements of the system. The O&M manual is
attached to this report as Appendix B.
3.1.1.4 Evaluation of Maintenance Requirements
Verification testing also evaluated the maintenance requirements of the treatment system. Not
all of the system's maintenance requirements were necessary due to the short duration of the
testing cycle. The O&M manual details various maintenance activities and their frequencies
(Pall, 1998). This information, as well as experience with common pieces of equipment (i.e.
pumps, valves etc.) was used to evaluate the maintenance requirements of the treatment system.
3.1.1 Equipment Characteristics
The qualitative, quantitative and cost factors of the tested equipment were identified, in so far as
possible, during the verification testing. The relatively short duration of the testing cycle creates
difficulty in reliably identifying some of the qualitative, quantitative and cost factors. The
qualitative factors examined during verification testing were susceptibility to changes in
environmental conditions, operational reliability, and equipment safety. The quantitative factors
examined during verification testing were power supply requirements, consumable requirements,
waste disposal technique, and length of operating cycle. The cost factors examined during
verification testing were power supply, consumables, and waste disposal. It is important to note
that the figures discussed here are for the Pall Corporation WPM-1 MF Pilot System. This
treatment unit operated at 77 gallons per square foot per day (gfd) at 3.8°C (120 gfd at 20°C).
Costs will increase with increasing flow.
3.2 Water Quality Consideration
Characterization of the treated water quality of the system was the driving force behind the
development of the experimental design of the ETV. The water quality and microbial analyses
were selected to demonstrate the treatment effectiveness of the manufacturer's equipment.
Treated water analyses (filtrate) and their frequencies are listed in Table 3-1.
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Table 3-1. Analytical Data Collection Schedule
Parameter Frequency Feed Filtrate Backwash Waste
Onsite Analytes
Temperature Daily 10 0
pH Daily 1 0 0
Turbidity Daily 2 Continuous 2
Particle Counts Daily Continuous Continuous 0
Chlorine Residual During Cleaning 1 (Backwash feed 0 1
water)
Laboratory Analytes
Total Alkalinity Monthly 110
Total Hardness Monthly 110
TDS Monthly 1 1 0
TSS Weekly 1 1 1
Total Coliforms Weekly 111
HPC Weekly 1 1 0
TOC Weekly 1 1 0
UVA254 Weekly 1 1 0
Algae Weekly 110
Giardia and Once during 3 Composite 0
Cryptosporidium challenge testing
3.3 Recording Data
Operational and water quality data was recorded to document the results of the verification
testing.
3.3.1 Operational Data
Operational data was read and recorded for each day of the testing cycle. The operational
parameters and frequency of readings are listed in Table 3-2 below.
Table 3-2. Operational Data Collection Schedule
Parameter Frequency
Raw Flow
2/day
Feed Water Temperature
1/day
Electric Power Use
1/day
Influent module/vessel pressure
2/day
Effluent module/vessel pressure
2/day
Filtrate pressure
2/day
Filtrate flow
2/day
In addition to these parameters, data was collected during chemical cleaning and membrane
integrity testing. Operational data collected during these tasks is discussed in Sections 3.8.2 and
3.8.5.
3.3.2 Water Quality Data
Table 3-1 lists the daily, weekly, and monthly water quality samples that were collected. The
results of the daily on-site analyses were recorded in the operations log book. The weekly and
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monthly laboratory analyses were recorded in laboratory log books and reported to the FTO on
separate laboratory report sheets. The data spreadsheets are attached to this report as Appendix
C.
3.4 Communications, Logistics and Data Handling Protocol
With the number of verification participants involved in the study it was important for the FTO
to coordinate communication between all parties. Documentation of study events was facilitated
through the use of logbooks, photographs, data sheets and chain of custody forms. Data handling
is a critical component of any equipment evaluation or testing. Care in handling data assures that
the results are accurate and verifiable. Accurate sample analysis is meaningless without
verifying that the numbers are being entered into spreadsheets and reports accurately and that the
results are statistically valid.
The data management system used in the verification testing program involved the use of
computer spreadsheet software and manual recording methods for recording operational
parameters for the membrane filtration equipment on a daily basis. Weekly and monthly water
quality testing data was submitted to the FTO by PWSA Laboratory representatives, verified,
and entered into computer spreadsheets.
3.4.1 Objectives
There were two primary objectives of the data handling portion of the study. One objective was
to establish a viable structure for the recording and transmission of field testing data such that the
FTO provides sufficient and reliable operational data for the NSF for verification purposes. A
second objective was to develop a statistical analysis of the data, as described in the "EPA/NSF
ETV Protocol for Equipment Verification Testing for Physical Removal of Microbiological and
Particulate Contaminants" (EPA/NSF 1998).
3.4.2 Procedures
The data handling procedures were used for all aspects of the verification test. Procedures
existed for the use of the log books used for recording the operational data, the documentation of
photographs taken during the study, the use of chains of custody forms, the gathering of inline
measurements, entry of data into the customized spreadsheets, and the methods for performing
statistical analyses.
3.4.2.1 Log Books
Field log books were bound with numbered pages and labeled with project name. The log book
is attached to this report as Appendix D. Log books were used to record equipment operating
data. Each line of the page was dated and initialed by the individual responsible for the entries.
Errors had one line drawn through them and the line was initialed and dated. Although the FTO
attempted to initial and date each page and individual line entries review of the log book at the
conclusion of testing indicated that in a few instances the entries had not been initialed. Field
testing operators recorded data and calculations by hand in laboratory notebooks. Daily
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measurements were recorded on specially prepared data log sheets. The laboratory notebook
was photocopied weekly. The original notebooks were stored on-site; the photocopied sheets
were stored at the office of the FTO. This procedure eased referencing the original data and
offered protection of the original record of results. Treatment unit operating logs included a
description of the membrane filtration equipment (description of test runs, names of visitors,
description of any problems or issues, etc); such descriptions were provided in addition to
experimental calculations and other items.
3.4.2.2 Photographs
Photographs were logged in the field log book. These entries include time, date, direction,
subject of photo and the identity of the photographer.
3.4.2.3 Chain of Custody
Samples which were collected by PWSA representatives and hand delivered to the laboratory
were logged into the laboratory's sample record upon arrival at the laboratory. During an audit
by NSF representatives, the use of chain of custody forms was requested. Subsequent samples
were collected and hand delivered to the laboratory accompanied by chain of custody forms.
The chain of custody forms are included in Appendix E.
3.4.2.4 Inline Measurements
Data from the computers recording the inline measurements were copied to disk at least on a
weekly basis. This information was stored on site and at the FTO's office.
3.4.2.5 Spreadsheets
The database for the project was set up in the form of custom-designed spreadsheets. The
spreadsheets are capable of storing and manipulating each monitored water quality and
operational parameter from each task, each sampling location, and each sampling time. All data
from the laboratory notebooks and data log sheets were entered into the appropriate spreadsheet.
Data entry into the spreadsheets was conducted at the FTO's office by designated operators. All
recorded calculations were also checked at this time. Following data entry, the spreadsheet was
printed out and the printout was checked against the handwritten data sheet. Any corrections
were noted on the hard copies and corrected on the screen, and then a corrected version of the
spreadsheet was printed out. Each step of the verification process was initialed by the field
testing operator or engineer performing the entry or verification step. Spreadsheet printouts are
included in Appendix C of this report.
3.4.2.6 Statistical Analysis
Water quality data developed from grab samples collected during filter runs, the operational data
recorded in the logbook, and the inline data were analyzed for statistical uncertainty. The FTO
calculated the average, minimum, maximum, standard deviation, and the 95% confidence
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intervals. The statistics developed are helpful in demonstrating the degree of reliability with
which water treatment equipment can attain quality goals.
3.5 Recording Statistical Uncertainty
The FTO calculated a 95% confidence interval for selected water quality parameters. These
calculations were also carried out on data from inline monitors and for grab samples of turbidity,
total coliform, HPC, TOC, TSS and TDS. The equation used is:
95% confidence interval = X ± tn_j 0975 (S /4n)
where: X is the sample mean;
S is the sample standard deviation;
n is the number of independent measurements included in the data set; and
t is the Student's t distribution value with n-1 degrees of freedom.
Results of these calculations are expressed as the sample mean +/- the statistical variation.
3.6 Verification Testing Schedule
The verification testing commenced on February 3, 1999 with the initiation of daily testing. The
unit ran in normal mode (XR flow, 77 gfd at 3.8°C flux [20 gfd at 20°C], 30-minute backwash
interval). Daily testing concluded on March 5. Data was logged for a total of 723 hours of
treatment system operation. Six hours of run time was lost due to a power failure at the pumping
station on March 3. Power was restored and the treatment unit was restarted after approximately
six hours of downtime.
Giardia and Cryptosporidium removal challenge testing was conducted February 5, 1999.
The cleaning efficiency task was performed on March 10, 1999. Membrane integrity testing was
done on March 11 after the conclusion of the cleaning evaluation.
3.7 Field Operations Procedures
In order to assure data validity, NSF Verification Testing Plan procedures were followed. This
ensured the accurate documentation of both water quality and equipment performance. Strict
adherence to these procedures resulted in verifiable performance of equipment.
3.7.1 Equipment Operations
The operating procedures for the Pall WPM-1 are described in the Operations Manual (Appendix
B) (Pall 1998). Analytical procedures are described in PWSA's Laboratory Quality Assurance
Plan (Appendix F) (PWSA 1997).
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3.7.1.1 Operations Manual
The Operations Manual for the treatment system was housed on-site and is attached to this report
as Appendix B. Additionally, operating procedures and equipment descriptions were described
in detail in Chapter 2 of this report.
3.7.1.2 Analytical Equipment
The following analytical equipment was used during the verification testing:
¦ A Fisher Accumet Model AP61 portable pH meter was used for pH analyses.
¦ A Hach 21 OOP portable turbidimeter was used for turbidity analyses.
¦ A Hach Pocket Colorimeter was used for chlorine analyses.
¦ An Ertco 1003-FC NIST traceable thermometer was used for temperature analyses. The
thermometer had a range -1 to 51°C with scale divisions of 0.1°C.
The treatment unit used a Hach 1720D turbidimeter for filtrate turbidity and Met One PCX
particle counters for particle analysis.
3.7.3 Initial Operations
Initial operations allowed the equipment manufacturer to refine the unit's operating procedures
and to make operational adjustments as needed to successfully treat the source water.
Information gathered during system start up and optimization would have been used to refine the
FOD (Appendix G), if necessary. No adjustment to the FOD was necessary as a result of the
initial operations. The unit was on site in February of 1998 conducting pilot testing for the
PWSA. The treatment system was operated until the start of the verification testing to establish
the optimum treatment scheme.
The major operating parameters examined during initial operations were flux, transmembrane
pressure, backwash frequency, and the percent water recovery of the treatment unit.
3.7.3.1 Flux
Production capacity of a membrane system is usually expressed as flux. Flux is the water flow
rate through the membrane divided by the surface area of the membrane. Flux is calculated from
the flow rate and membrane surface area and it is expressed as gfd. The surface area of the
membrane used for the verification testing was 75 ft2. It is customary to refer to flux normalized
to 20°C (68°F). Lower temperatures increase the viscosity of water and decrease the amount of
permeate that can be produced from a given area.
The feed pressure to the membrane is adjusted to maintain the selected flux. This usually
requires an increase in feed pressure to maintain the selected flux. In order to take this change in
feed pressure into account, a parameter known as specific flux can be calculated. Specific flux is
calculated by dividing the flux of the system by the transmembrane pressure. The specific flux is
expressed in gallon per square foot per day per pounds per square inch (gfd/psi) at 68°F.
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3.7.3.2 Transmembrane Pressure
The pressures of the feed water were recorded twice per day. Since the Pall unit utilizes XR
flow the pressure of the retentate is also recorded. The average of these two readings is used as
the feed pressure to the system. The filtrate pressure was recorded twice per day. The amount
of pressure lost as the water is filtered through the membrane is referred to as transmembrane
pressure (TMP).
3.7.3.3 Backwash (Reverse Filtration)
As water is filtered through the membrane surface, a film of rejected particulates accumulates on
the surface of the fibers. With greater accumulation, this gradually impedes the permeate flow.
To maintain stable flow over the short term, a periodic RF cleaning cycle is performed. RF is a
cleaning method used to keep module flux high. It is analogous to "backwashing" where filter
flow is reversed. The reverse flow allows the particles trapped at the membrane to free the
membrane pores and direct their exit from the system. This eliminates the flow restriction arising
from particles plugging membrane pores.
RF typically takes place every 15-30 minutes. In the RF cleaning, the feed flow is stopped, and
clean permeate is pumped backwards through the module from the inside of the fibers out
through the pores. Typically, RF rate of flow is fixed at around 1.5-2 times the forward flow
rate, washing away the accumulated contaminates. This reverse flow is short lived - a typical RF
duration could be 20 seconds of every 24 minutes. This RF water exits the XR port near the top
of the module. RF is generally diverted to drain to prevent the concentrated contaminants from
reentering the flow path. Drainage of RF constitutes the majority of the lost feed flow
(approximately 5%).
To aid in cleaning the module, and particularly in removing any bio-burden on the membrane
surfaces, chlorine, in the form of 12.5% sodium hypochlorite, is injected into the RF flow stream.
The level of chlorine in the RF feed is approximately 20 mg/L. Valves direct all chlorine-laden
RF- clean flow to waste.
Reverse filtration is not totally effective in cleaning the membrane fibers, and occasionally AS, a
more vigorous cleaning, is required. AS is a two step process. The first step consists of bubbling
about 3 scfm of compressed air through each module with no water flow. The air is introduced
into the feed connection of the module. Gaseous air will not pass through the fibers, so this air
stays on the feed side of the membrane. The air bubbles shake the fibers, sloughing off material
that resists the RF cycle.
The second part of the AS cycle serves as a rinse and flush. Air is still bubbled up through the
module, but water is also circulated through the feed side of the module. This is even more
effective in cleaning the module surface. Air Scrubbing is an energetic process. For this reason,
the number of AS cycles must be kept to the minimum required to keep the modules clean.
For this test program, a RF interval of once every 30 minutes was used. Every other RF cycle i.e.
once every hour utilized an AS cycle. The unit used approximately 3 gallons of permeate to
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backwash the membranes each cycle during a RF cycle. AS followed by RF required 6.2 gallons
of permeate.
3.7.3.4 Percent Feed Water Recovery
In order to calculate the percent water recovery of the treatment system, the net production of the
unit is divided by the total production of the unit. Multiplying the average flow rate by the
filtration run time gives the total amount produced for the run. The net production is calculated
by subtracting the amount of permeate required to backwash the system from the total amount
produced. Dividing the net production by the total production and multiplying the result by 100
equals the percent water recovery of the system.
3.8 Verification Task Procedures
The procedures for each task of the verification testing were developed in accordance with the
requirements in the EPA/NSF ETV Protocol (EPA/NSF 1998). The Verification Tasks were as
follows:
¦ Task 1 Membrane Flux and Operation
¦ Task 2 Cleaning Efficiency
¦ Task 3 Finished Water Quality
¦ Task 4 Reporting of Maximum Membrane Pore Size
¦ Task 5 Membrane Integrity Testing
¦ Task 6 Microbial Removal
Detailed descriptions of each task are provided in the following sections.
3.8.1 Task 1: Membrane Flux and Operation
Membrane flux and operational characteristics were identified in this task. The purpose of this
evaluation was to quantify operational characteristics of the MF equipment. Information
regarding this task was collected throughout the length of the 30-day verification study.
The objectives of this task were to:
1. Establish appropriate operational parameters;
2. Demonstrate the product water recovery achieved;
3. Monitor the rate of flux decline over extended operation; and
4. Monitor raw water quality.
Standard operating parameters for filtration, backwash, and chemical cleaning were established
through the use of the manufacturer's O&M Manual and the initial operations of the treatment
system. After establishment of these parameters, the unit was operated under those conditions.
Operational data was collected according to the schedule presented in Table 3-2.
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3.8.1.1 Filtration
The flux selected for the verification study was 77 gfd at 3.8°C (120 gfd at 20°C). The rate was
selected by the manufacturer after examination of the initial operation data.
3.8.1.2 Backwash
The filtration cycle was 30 minutes for the verification study. The duration of the RF was 30
seconds.
The interval between backwashes is determined based on the ability of the unit to maintain a
stable flow over the short term. That is, if the backwash frequency is not able to maintain a
stable flow over the short term, it is increased. The backwash frequency used during the study
was capable of maintaining a stable flow.
The procedure for backwashing is detailed in the O&M Manual (Appendix B). The normal
backwash is an automatic function of the unit; the only adjustments which can be made are to
frequency, duration, and pressure. Procedures for making these adjustments are detailed in the
O&M Manual.
3.8.1.3 Chemical Cleaning
Chemical cleaning was to be instituted when the backwashing sequence was unable to maintain
system TMP below 30 pounds per square inch differential (psid).
The cleaning was a two-stage process consisting of a citric acid cleaning and a caustic/chlorine
cleaning. The citric acid cleaning consists of mixing a 2% citric acid solution, adding the
solution to the membrane module, allowing the membrane to soak for one half hour, circulating
the solution through the treatment system for 20-30 minutes. The system is then put through a
RF cycle to rinse the citric acid solution from the system. The caustic/chlorine cleaning consists
of mixing a 0.1N NaOH solution. Four hundred mg/1 NaOCl is added to the caustic solution.
The solution is added to the membrane module and the membrane is soaked for one hour. The
solution is then recirculated for one hour. The system is then put through a RF cycle to rinse the
caustic/chlorine solution from the system. The cleaning solutions were heated to 27°C - 38°C.
The manufacturer recommends heating the cleaning solution when the temperature of the
permeate water is less than 15°C. According to the manufacturer, the heated cleaning solutions
maintains the solubility of the chemicals in the solutions and enhances the cleaning of the
membrane. A detailed description of the cleaning process is in the manufacturer's O&M Manual
(Appendix B).
3.8.2 Task 2: Cleaning Efficiency
Cleaning efficiency procedures were identified in this task. The objectives of this task were to:
1. Evaluate the effectiveness of chemical cleaning for restoring finished water productivity to
the membrane system.
2. Confirm manufacturer's cleaning practices are sufficient to restore membrane productivity.
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Chemical cleaning, if required during the testing period, was to be instituted when the
backwashing sequence was unable to maintain system TMP below 30 psid. If chemical cleaning
was not required during the testing, it was to be performed at the conclusion of the 30-day
period. The membranes were cleaned using manufacturer's recommendations March 10, 1999.
Prior to cleaning, the treatment system was operated at the conditions as described in Section
3.8.1. Operational data, including flow and pressure, were collected prior to cleaning. After
cleaning the system was restarted and operated a sufficient period of time to establish post
cleaning, specific rate of flux recovery. Operational data, including flow and pressure, were
collected after cleaning. Table 3-3 details all the operational and analytical data collected before,
during, and following cleaning.
Table 3-3. Analytical & Operational Data Collection Schedule - Chemical Cleaning
Parameter Frequency
pH of cleaning solution initial
1/episode
pH of cleaning solution during process
1/episode
pH of cleaning solution final
1/episode
TDS of cleaning solution initial
1/episode
TDS of cleaning solution during process
1/episode
TDS of cleaning solution final
1/episode
Turbidity of cleaning solution initial
1/episode
Turbidity of cleaning solution during process
1/episode
Turbidity of cleaning solution final
1/episode
Oxidant residual initial
1/episode
Oxidant residual final
1/episode
Visual observation of backwash waste initial
1/episode
Visual observation of backwash waste final
1/episode
Flow of MF unit prior to cleaning
1/episode
Pressure of MF unit prior to cleaning
1/episode
Temperature of MF unit prior to cleaning
1/episode
Flow of MF unit after cleaning
1/episode
Pressure of MF unit after cleaning
1/episode
Temperature of MF unit after cleaning
1/episode
3.8.2.1 Cleaning Procedures
The procedure used to perform chemical cleaning is presented in the O&M Manual (Appendix
B). The chemical cleaning process can be summarized in the following steps:
1. Put the system in Manual Mode, and fill the Permeate Tank.
2. Drain the feed side of the system.
3. Fill the feed tank with permeate and chemicals.
4. Recirculate cleaning solution.
5. Reduce chlorine in the solution and drain.
6. Fill the Permeate Tank with water and chemicals.
7. Recirculate cleaning solution on permeate side of system.
8. Pump solution into interconnect piping, and soak.
9. Reduce chlorine and pump down permeate side.
10. Flush system.
11. Place in Automatic and restart system.
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A recording table is included in the O&M manual to record pump speeds, chemicals used, etc.
during each chemical cleaning operation. These data may be useful in tracking system
performance, or reducing the amount of time that the cleaning cycle requires.
For the verification testing, a chemical cleaning solution of 0.1N caustic soda plus 400 parts per
million (ppm) of sodium hypochlorite was recirculated through the membranes for 1 hour and
then 2% citric acid was recirculated through the membranes for V2 hour. Approximately 100
gallons of both solutions were used. The manufacturer recommended heating the solutions to
27-3 8°C to enhance the solubility of the cleaning chemicals and to maintain the solubility of the
chemicals in the solutions because the temperature of the permeate water was less than 15°C.
3.8.3 Task 3: Finished Water Quality
Procedures for the collection and analysis of finished water quality samples are identified in this
task. The purpose of this task was to demonstrate whether the manufacturer's stated treatment
capabilities are attainable. The goal of this portion of the ETV was to demonstrate the treatment
unit's ability to consistently produce water with a turbidity of less than <0.1 NTU and also to
comply with current and future regulations in the SWTR and ESWTR as they apply to filtration.
Since the feed water turbidity was consistently less than 0.1 NTU and a turbidity challenge was
not conducted this stated treatment goal was not verifiable.
Testing on finished water was conducted throughout the length of the 30-day run. Procedures for
sample collection and analysis, analytical equipment operation, analytical equipment calibration
and calibration results are discussed in Section 3.8.3.1.
3.8.3.1 Sample Collection and Analysis Procedure
Finished water samples were collected and analyzed monthly for total alkalinity, total hardness,
and TDS. Weekly collection and analysis of finished water samples was performed for TSS,
total coliforms, HPC, TOC, UVA254, and algae. A summary of the sampling schedule is
presented in Table 3-1.
Sample collection and analysis was performed according to procedures adapted from Standard
Methods (APHA et.al., 1992) and Methods for Chemical Analysis of Water and Wastes (EPA,
March, 1979).
3.8.4 Task 4: Reporting of Maximum Membrane Pore Size
Determination of the maximum membrane pore size was to be done to assess a MF unit's ability
to sieve particles of particular sizes. The FTO was to conduct a bubble point test, air pressure
hold test, diffusive air flow test, or sonic wave sensing on the type of membrane in use during the
verification study. The test was to be conducted by a state or EPA certified laboratory. Due to
the extremely high cost of this test and the reliability of data available from membrane
manufacturers, the ETV Steering Committee modified this requirement. The 1999 ETV Protocol
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Revision requires the reporting of the maximum membrane pore size by the manufacturer based
on recommendation by the Steering Committee (EPA/NSF 1999).
The manufacturer requested a waiver to permit the reporting of maximum membrane pore size in
lieu of maximum pore size determination. This waiver was granted based on the modified ETV
Protocol requirement (EPA/NSF 1999).
3.8.5 Task 5: Membrane Integrity Testing
Procedures for the testing of membrane integrity are identified in this task. The experimental
objective of this task was to assess the membrane's integrity through the use of an air pressure
hold test, turbidity reduction monitoring and particle count reduction monitoring. Membranes
provide a mechanical barrier against the passage of particles and most types of microbial
contamination. If the membrane is compromised, that is not intact, this barrier is lost. It is
important to be able to detect when a membrane is compromised.
The three procedures, air pressure hold test, turbidity reduction monitoring, and particle count
reduction monitoring, were conducted on intact and compromised membranes. The tests were
conducted prior to and after the intentional breaking of a fiber.
3.8.5.1 Air Pressure Hold Test
In order to conduct this test, it was necessary to remove the membrane vessel from the treatment
unit. The membrane unit filtrate side was drained. The membrane itself was fully wetted (i.e.
membrane pores were filled with water). The membrane was air pressurized up to 15 psi. The
filtrate side was sealed and the pressure decline rate was monitored every thirty seconds using an
air pressure gauge. An intact membrane would be demonstrated by minimal pressure loss, i.e. 1
psi every 5 minutes. Air pressure loss was also compared to the loss that was obtained when
testing a compromised membrane.
3.8.5.2 Turbidity Reduction Monitoring
Turbidity of feed and filtrate water was continuously monitored. An intact membrane would be
expected to show a 90% reduction in turbidity from feed to filtrate. Due to the high quality of
the feed water (the average feed turbidity was 0.088 NTU) showing a 90% reduction, 0.0088
NTU, was beyond the capability of the turbidimeters. Filtrate turbidity between an intact and a
compromised membrane was compared. An increase of 100% was used as an indication of a
compromised membrane.
3.8.5.3 Particle Count Reduction Monitoring
Particle count reductions from source to finished water of 99.9% would demonstrate an intact
membrane. Due to the high quality of the feed water (the average cumulative feed water particle
counts were 120 total counts per ml) showing a 99.9% reduction was pushing the limits of the
instrumentation. Particle counts were monitored continuously and the differences between
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filtrate particle counts from an intact and a compromised membrane were compared. An
increase of 100% was used as an indication of a compromised membrane.
3.8.6 Task 6: Giardia and Cryptosporidium Removal
The primary goal of water treatment is to provide water that is free of disease causing organisms.
Most of these organisms are removed or rendered non-infectious through the use of conventional
treatment practices like sedimentation, filtration, and disinfection. Not all disease producing
organisms are reliably removed by these conventional processes. Membrane filtration offers the
advantage of providing a physical barrier against the passage of two of these organisms, Giardia
and Cryptosporidium.
The purpose of this task was to demonstrate the treatment unit's ability to provide a minimum 3
logio removal from source water to plant effluent of Giardia cysts and 2 logio removal of
Cryptosporidium oocysts. Participation in this task was optional. The manufacturer opted to
participate in the microbial removal challenge.
Giardia and Cryptosporidium challenge testing took place on February 5, 1999. The procedures
for the preparation of the feed water stock, stock addition, sample collection and analysis, and
calibration are presented below.
Procedures for testing the effectiveness of the treatment system in removing Giardia cysts and
Cryptosporidium oocysts are identified in this section. The testing schedule, the experimental
objectives, procedures, and data collection schedule are discussed below.
3.8.6.1 Feed Water Stock Preparation
Challenge organisms were concentrated stock suspensions of formalin fixed Giardia lamblia
cysts and formalin fixed Cryptosporidium parvum oocysts. The suspensions were added to a
reservoir using a pipette as that reservoir was being filled with 50 gallons of feed water. A
cocktail of both protozoans was added to the same feed water reservoir and fed simultaneously to
the treatment system. The concentration of the organisms was determined from the stock
suspensions by replicate hemocytometer. Five two ml samples were taken from the feed water
reservoir. These samples were examined and the quantity of cysts and oocysts were determined.
This was used as a check of the replicate hemocytometer counts.
3.8.6.2 Stock Addition Procedure
Source water concentrations were fed into the treatment system immediately before the
membrane vessels over approximately 60 minutes. Seeding began immediately after a backwash
cycle. The feed water stock reservoir was gently mixed during this process.
3.8.6.2 Sample Collection Procedure
After the suspension was prepared and before the initiation of filtration, samples were collected
to establish the initial titer of the microorganisms. The feed suspension was pumped into the feed
water line immediately before the membrane vessels. Once filtration had begun, the operational
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parameters, as presented in Table 3-2, were recorded. Daily analytical testing as presented in
Table 3-1 was conducted. One thousand liters (264 gallons) of permeate water were then passed
through a l|im pore sized yarn wound filter at a rate of one gallon per minute (3.785 liter per
minute). Sample volumes of feed water, filtrate water and back washwater were recorded.
Samples were processed and analyzed by PWSA's EPA qualified laboratory according to EPA
protocols. (EPA, April, 1996). A minimum of three replicates of the filtered water sample were
analyzed.
3.9 QA/QC Procedures
Maintenance of strict quality assurance and quality control (QA/QC) procedures is important, in
that if a question arises when analyzing or interpreting data collected for a given experiment, it
will be possible to verify exact conditions at the time of testing. The following QA/QC
procedures were utilized during the verification testing.
3.9.1 Daily QA/QC Verification Procedures
Daily QA/QC procedures were performed on the inline turbidimeter and inline particle counter
flow rates and inline turbidimeter readout.
3.9.1.1 Inline Turbidimeter Flow Rate
The inline turbidimeter flow rate was verified volumetrically over a specific time. Effluent from
the unit was collected into a graduated cylinder while being timed. Acceptable flow rates, as
specified by the manufacturer, ranged from 250 ml/minute to 750 ml/minute. The target flow
rate was 500 ml/minute. Adjustments to the flow rate were made by adjusting the valve
controlling flow to the unit. Fine adjustments to the flow rate were difficult to make. If
adjustments to the flow rate were made they were noted in the operational/analytical data log
book by including the flow rate prior to adjustment in parentheses next to the description of what
adjustment was made.
3.9.1.2 Inline Particle Counter Flow Rate
The flow rate for the feed water and filtrate inline particle counters were verified volumetrically
over a specific time. Effluent from the units was collected into a graduated cylinder while being
timed. Acceptable flow rates, as specified by the manufacturer, ranged from 90 ml/minute to
110 ml/minute. The target flow rate was 100 ml/minute. Care was taken to maintain the flow
rate between 95 ml/minute and 105 ml/minute. Changes to the flow rate were made by adjusting
the level of the discharge from the overflow weir. If adjustments to the flow rate were made they
were noted in the operational/analytical data log book by including the flow rate prior to
adjustment in parentheses next to the description of what adjustment was made.
3.9.1.3 Inline Turbidimeter Readout
Inline turbidimeter readings were checked against a properly calibrated bench model. Samples
of the filtrate were collected and analyzed on a calibrated bench turbidimeter. The readout of the
27
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bench model and the online turbidimeter were recorded. Exact agreement between the two
turbidimeters is not likely due to the differences in the analytical techniques of the two
instruments.
3.9.2 Bi-Weekly QA/QC Verification Procedures
Bi-weekly QA/QC procedures were performed on the inline flow meter. Meter was checked to
determine if cleaning was necessary and verification of flow was performed.
3.9.2.1 Inline Flow Meter Clean Out
Examination of the inline flow meters indicated that clean out was not required during the
verification testing. This was due to the short duration of the study and the high quality of the
feed water.
3.9.2.2 Inline Flow Meter Flow Verification
Verification of the readout of the permeate, and retentate flow meters was conducted bi-weekly
during the testing period. This was done by taking the difference in the totalizer reading over a
specific period of time and comparing it to a volume collected over the same time period. The
permeate meter was verified by collecting the entire volume of permeate over a timed period and
comparing the amount collected to the totalizer readings. The retentate meter was verified by
collecting the retentate returning to the feed water tank over a timed period and comparing it to
the flow rate displayed on the retentate flow meter. Due to the small volume of retentate that
could be collected the totalizer reading could not be used.
3.9.3 Procedures for QA/QC Verifications at the Start of Each Testing Period
Verifications of the inline turbidimeter, pressure gauges/transmitters, tubing, and particle
counters were conducted. These verification procedures follow.
3.9.3.1 Inline Turbidimeter
The inline turbidimeter reservoir was cleaned by removing the plug from the bottom of the unit
and allowing the body to drain. The body of the unit was then flushed with water. The unit was
recalibrated following manufacturer's recommendations.
3.9.3.2 Pressure Gauges / Transmitters
Pressure gauge readouts were compared to the display on the control screen, although the
readings taken directly from the gauges were entered into the operational/analytical data log
book. Pressure gauge readings were verified through the use of a dead test meter. Procedures
for the use of the meter were included with the meter. Generally, the procedure consisted of
placing the gauge on the meter adding weight to the meter and comparing the reading obtained to
the known amount of weight.
28
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3.9.3.3 Tubing
The tubing and connections associated with the treatment system were inspected to verify that
they were clean and did not have any holes in them. Also, the tubing was inspected for
brittleness or any condition which could cause a failure.
3.9.3.4 Inline Particle Counters
Calibration of the particle counter is generally performed by the instrument manufacturer. The
calibration data was provided by the instrument manufacturer for entry into the software
calibration program. Once the calibration data was entered it was verified using calibrated
mono-sized polymer microspheres. Microspheres of 5wm, lOwm and 15wm were used for
particle size verification. The following procedure was used for instrument calibration
verification:
¦ Analyze the particle concentration in the dilution water;
¦ Add an aliquot of the microsphere solution to the dilution water to obtain a final
particle concentration of 2,000 particles per ml;
¦ Analyze a suspension of each particle size separately to determine that the peak
particle concentration coincides with the diameter of particles added to the dilution
water;
¦ Prepare a cocktail containing all three microsphere solutions to obtain a final particle
concentration of approximately 2,000 particles per ml of each particle size; and
¦ Analyze this cocktail to determine that the particle counter output contains peaks for
all the particle sizes.
3.9.4 On-Site Analytical Methods
Procedures for daily calibration, duplicate analysis, and performance evaluation for pH,
temperature, residual chlorine are discussed in the following sections.
3.9.4.1 pH
Analysis for pH was performed according to Standard Methods 4500-H+. A two-point
calibration of the pH meter was performed each day the instrument was in use. Certified pH
buffers in the expected range were used. After the calibration, a third buffer was used to check
linearity. The values of the two buffers used for calibration, the efficiency of the probe
(calculated from the values of the two buffers), and the value of the third buffer used as a check
were recorded in the logbook.
pH measurements do not lend themselves to "blank" analyses. Duplicates were run once a day.
Performance evaluation samples were analyzed during the testing period. Results of the
duplicates and performance evaluation were recorded.
29
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3.9.4.2 Temperature
Readings for temperature were conducted in accordance with Standard Methods 2550. Raw
water temperatures were obtained once per day by submerging the thermometer in the feed water
reservoir. A National Institute of Standards and Technology (NIST) certified thermometer
having a range of - 1°C to +51°C, subdivided in 0.1°C increments was used for all temperature
readings.
Temperature measurements do not lend themselves to "blank" analyses. Duplicates were run on
every sample. The temperature of the feed water was not recorded until two like readings were
obtained, indicating that the thermometer had stabilized. Two equivalent readings were
considered to be duplicate analyses.
3.9.4.3 Residual Chlorine Analysis
Chlorine residual analyses were taken on the backwash waste according to Standard Methods
4500-C1 G. The unit was received new (factory calibrated) and daily calibration was not
necessary.
The backwash wastewater was collected, during backwash, twice per day. The entire amount of
wash water from a backwash was collected in a reservoir for analysis. Dilution of the backwash
waste (1ml of backwash waste to 5ml deionized [DI] water) was necessary due to the high level
of residual total chlorine.
Blanks for chlorine analyses were done by analyzing DI water daily. Duplicates were run once a
day. Performance evaluation samples were analyzed during the testing period. Results of the
duplicates and performance evaluation were recorded.
3.9.4.4 Turbidity Analysis
Turbidity analyses were performed according to Standard Methods 2130. The bench-top
turbidimeter was calibrated at the beginning of verification test and on a weekly basis using
primary turbidity standards according to manufacturer's recommendations. Primary turbidity
standards of 0.1, 0.5 and 5.0 NTU were checked after calibration to verify instrument
performance. Deviation of more than 10 % of the true value of the primary standards indicated
that recalibration or corrective action should be undertaken on the turbidimeter. Secondary
standards were used on a daily basis to verify calibration.
Blanks for turbidity analyses were done by analyzing DI water daily. Duplicates were run on
feed water turbidity and backwash waste once a day. Performance evaluation samples were
analyzed during the testing period. Results of the duplicates and performance evaluation were
recorded.
30
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3.9.5 Chemical and Biological Samples Shipped Off-Site for Analyses
PWSA's in-house laboratory was used for the analysis of chemical and biological parameters.
PWSA's QA Plan outlines sample collection and preservation methods (PWSA 1997) (Appendix
F). Sample collection was done by representatives of PWS A.
3.9.5.1 Organic Parameters
Organic parameters analyzed during the verification testing were TOC and UVA254- Samples for
analysis of TOC and UVA254 were collected in glass bottles supplied by the PWS A laboratory
and hand carried to the laboratory by a PWSA representative immediately after collection. TOC
and UVA254 samples were collected, preserved, and held in accordance with Standard Method
5010B. Storage time before analysis was minimized in accordance to Standard Methods.
Analyses of the TOC samples were done according to methodology outlined in PWSA's QA
Plan which is based on Standard Methods 5310 C. Analyses of the UVA samples were done
according to methodology outlined in PWSA's QA Plan which is based on Standard Methods
5910 B.
3.9.5.2 Microbiological Parameters
Microbiological parameters analyzed during the verification testing were Total Coliform, HPC,
Protozoa, Algae, Giardia and Cryptosporidium. Microbiological samples were collected
according to procedures outlined in PWSA's QA Plan and hand delivered to the laboratory by a
PWSA representative immediately following collection. Samples were processed for analysis by
the PWSA laboratory within the time specified for the relevant analytical method. The
laboratory kept the samples refrigerated at 1-5°C until initiation of analysis.
Algae samples were preserved with Lugol's solution after collection and stored at a temperature
of approximately 1-5°C until counted. Lugol's solution is prepared by dissolving 20 grams of
potassium iodide and 10 grams iodine crystals in 200ml of distilled water containing 20 ml of
glacial acetic acid.
Algae samples were analyzed according to Standard Method 10200 F. Total coliforms were
analyzed using procedures presented in PWSA's QA Plan. These procedures are based on
Standard Methods 9222B. HPC analyses were conducted according to procedures presented in
PWSA's QA plan. These procedures are based on Standard Methods 9215D. Protozoans were
analyzed using procedures developed by EPA for use during the Information Collection Rule
(EPA, 1996).
3.9.5.3 Inorganic Parameters
Inorganic parameters analyzed during the verification testing were Total Alkalinity, Total
Hardness, TDS, and TSS.
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Inorganic chemical samples were collected, preserved and held in accordance with Standard
Methods 301 OB. Particular attention was paid to the sources of contamination as outlined in
Standard Method 3010C. The samples were hand delivered to the laboratory by a representative
of PWSA immediately following collection. The laboratory kept the samples at approximately
1-5° C until initiation of analysis.
Total alkalinity analyses were conducted according to Method 150.1 (EPA, 1979). Total
Hardness analyses were conducted according to Method 130.2 (EPA, 1979). TDS analyses
were conducted according to Standard Methods 2540C. TSS analyses were conducted according
to Standard Methods 2540D.
32
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Chapter 4
Results and Discussion
4.1 Introduction
The verification testing for the Pall Corporation WPM-1 Pilot System which occurred at the
PWSA's Highland Reservoir No. 1 site in Pittsburgh, Pennsylvania, commenced on February 3,
1999, and concluded its 30-day period on March 5, 1999. Giardia and Cryptosporidium
challenge testing was conducted on February 5, 1999, chemical cleaning was performed on
March 10, 1999, and membrane integrity testing was performed on March 11, 1999.
This section of the verification report presents the results of the testing and offers a discussion of
the results. Results and discussions of the following are included: initial operations, equipment
characteristics, membrane flux and operation, cleaning efficiency, finished water quality,
maximum membrane pore size, membrane integrity testing, and Giardia and Cryptosporidium
removal, and QA/QC.
4.2 Initial Operations Period Results
An initial operations period allowed the equipment manufacturer to refine the unit's operating
procedures and to make operational adjustments as needed to successfully treat the source water.
The primary goals of the initial operations period were to establish a flux rate, the expected
transmembrane pressure, backwash frequency appropriate for the feed water quality, and the
efficiency of the unit. The unit was on site in February 1998 until the end of ETV testing and
was operated to establish the optimum treatment scheme prior to initiation of verification testing.
4.2.1 Flux
Flux rates from 59 to 161 gfd at 20°C were examined during the initial operations period. Based
on the data collected during the initial operations period, the manufacturer determined that the
treatment unit would be capable of operating at 120 gfd at 20°C (82 l/m2/h at 20°C) (which
equates to 77 gfd at 3.8°C, the temperature of the feed water during testing). This corresponded
to an initial specific flux of 5.4 gfd/psi at 20°C when the TMP at time zero of testing is taken into
account.
4.2.2 Transmembrane Pressure
The TMP during the initial operations period varied with the flux. TMP ranged from 3.6 psi to
29.6 psi during the initial operations period.
4.2.3 Backwash Frequency
During the initial operations period, backwash frequencies of 30 and 60 minutes were
investigated. Based on the results of the initial operations period, it was determined that a
backwash would occur every 30 minutes alternating between RF and AS cycles. That is the first
backwash in an hour would be a RF cycle. The next backwash would be an AS cycle followed
33
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by a RF cycle. This alternating pattern was maintained throughout the verification testing. The
RF duration was 30 seconds; the AS cycle was 60 seconds. This backwash scenario proved to be
appropriate for flux maintenance during the study. The amount of permeate used during a RF
cycle was approximately 3 gallons; AS followed by RF required 6.2 gallons of permeate.
4.3 Verification Testing Results and Discussion
The results and discussions of membrane flux and operation, cleaning efficiency, finished water
quality, reporting of maximum membrane pore size, membrane integrity testing, and Giardia and
Cryptosporidium removal tasks of the verification testing are presented below.
4.3.1 Task 1: Membrane Flux and Operation
The parameters of flow, feed and filtrate pressures, backwash frequency and volumes, and the
feed water temperature were used to establish membrane flux and operational characteristics.
TMP and rate of specific flux decline were established from these parameters. The results of the
TMP and rate of specific flux decline are presented below. Date of chemical cleaning was
March 10, 1999. A calculation of the feed water recovery of the treatment system is presented.
4.3.1.1 Transmembrane Pressure Results
Transmembrane pressure fluctuated from 22 to 26 psid during the 30 day testing. The average
TMP during the testing was 24 psid. Table 4-1 presents a summary of the daily unit pressure
readings and TMP. Figure 4-1 presents a graph of daily TMP results. A complete tabular
summary of the data is presented in Appendix C.
Table 4-1. Daily Unit Pressure Readings and Transmembrane Pressure
Feed Pressure
Retentate Pressure
Filtrate Pressure
T ransmembrane
Pressure
(psi)
(psi)
(psi)
(psid)
Average
30
28
5.1
24
Minimum
27
25
3.4
22
Maximum
32
31
5.9
26
Standard Deviation
1.4
1.3
0.57
1.1
Confidence Interval
(29, 30)
(28,29)
(4.9, 5.2)
(24,24)
34
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Transmembrane Pressure vs. Time
Run Time (hours)
Figure 4-1. Transmembrane Pressure vs. Time
As depicted in Figure 4-1, the TMP increased slightly over the course of the verification testing.
This slight increase was not unexpected and seemed to indicate that the treatment system was
capable of operation at the selected flux and backwash protocol on this feed water.
The increase in TMP may be due to the accumulation of particles on the membrane surface. The
backwash protocol may not have removed all of the particulate material from the membrane.
Another possibility is that there was some accumulation of algae or bacteria on the membrane.
(The addition of chlorine to the backwash water is intended to control the accumulation of these
substances.) An accumulation of material on the membrane would, most likely, cause an
increase in TMP in the system by limiting the available membrane surface area.
The TMP fluctuated somewhat from day to day with subsequent day's readings sometimes being
lower than the previous day's results. This would seem to argue against the accumulation of
material on the membrane. But examination of the overall TMP trend clearly shows an increase
with time. The explanation of why TMP sometimes decreased from day to day may be due to the
fact that the operational readings were taken at various times in the operational cycle. The feed
pressure increased as the time to the next backwash decreased. If the pressure and flow readings
were taken shortly after the completion of a backwash cycle, a lower TMP would result.
Likewise if the readings were taken just prior to the initiation of a backwash cycle, a higher TMP
would result.
There was a noticeable decrease in TMP between run time 650 hours and 695 hours. This may
have been related to the system shut down caused by a power failure which occurred on March 3.
35
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Allowing the membranes to "relax" may have caused some of the accumulated particles to be
released from the membranes. There is no empirical evidence for this supposition. The decrease
in TMP between run time 845 hours and 850 hours was a result of the chemical cleaning process.
Overall, the increase in TMP during the 30-day testing period was slight. This would seem to
indicate that the selected flux and backwash protocol was appropriate for this feed water quality.
4.3.1.2 Specific Flux Results
The specific flux of the treatment system ranged from 4.6 to 5.5 gfd/psi at 20°C (45 to 54
l/m2/h/b at 20°C) and on average was 5.0 gfd/psi at 20°C (50 l/m2/h/b at 20°C) during the 30-day
verification test period. Table 4-2 presents a summary of the specific flux of the treatment system
during the 30-day test period. Figure 4-2 presents a graph of daily specific flux results during the
30-day test period and during the cleaning operations that occurred after the 30-day test.
Table 4-2. Specific Flux
Specific Flux during 30-day test period
(gfd/psi @20°C)
Average 5.0
Minimum 4.6
Maximum 5.5
Standard Deviation 0.22
Confidence Interval (5.0, 5.1)
Specific Flux vs. Time
Chemical Cleaning
1/
V
¦—h—. ———
^ 30-Day Tesl Pel iod >
® a* & & Nt» ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ <£> # $ ^ £ £>
Run Time (hours)
Figure 4-2. Specific Flux Decline vs. Time
36
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As depicted in Figure 4-2, specific flux slightly declined over the course of the verification
testing. The specific flux is a function of the flux and the TMP of the system. As the TMP of
the system increases the specific flux declines. The decrease in specific flux during the testing
period was due to the increase in TMP. The specific flux decline did not appear to be excessive
during the testing. That is, the unit appeared to be capable running at the selected conditions
during the verification testing.
The sharp increase in specific flux on March 10 was a result of the chemical cleaning process.
4.3.1.3 Cleaning Episodes
Pall recommends that cleaning be instituted when the backwashing sequence is unable to
maintain system TMP below 30 psid. The membranes were cleaned as per protocol requirements
using manufacturer's recommendations March 10, 1999. Results of that cleaning are presented
in Section 4.3.2.
4.3.1.4 Percent Feed Water Recovery
The percent feed water recovery of the treatment system was calculated by comparing the net
production to the total water filtered. The following equation was used:
Percent feed water recovery = 100 * [Qp/Qf]
Where: Qp = filtrate flow (gpd)
Qf = feed flow to membrane
Using the above equation the following calculation was performed:
Filtrate flow = flow (gpm) * minutes/day = filtrate flow (gpd)
Filtrate flow = 4.0 gpm* 1440 minute/day = 5760 gpd
Feed flow to membrane = filtrate flow + backwash volume
Feed flow = 5760 gpd + (3 gal/backwash/hr * hr/day)
+ (6.2 gal/backwash with AS/hr * hr/day) = 5980 gpd
Percent feed water recovery = 100 * [5760/5980] = 96%
4.3.2 Task 2: Cleaning Efficiency
Cleaning was conducted March 10, 1999. The cleaning was a two-stage process consisting of a
citric acid cleaning and a caustic/chlorine cleaning. The citric acid cleaning consists of mixing a
2% citric acid solution, adding the solution to the membrane module, allowing the membrane to
soak for one half hour, circulating the solution through the treatment system for 20-30 minutes.
The system is then put through a RF cycle to rinse the citric acid solution from the system. The
caustic/chlorine cleaning consists of mixing a 0.1N NaOH solution. 400 mg/1 NaOCl is added to
the caustic solution. The solution is added to the membrane module and the membrane is soaked
for one hour. The solution is then recirculated for one hour. The system is then put through a
RF cycle to rinse the caustic/chlorine solution from the system. The cleaning solutions were
37
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heated to 27°C - 38°C. The manufacturer recommends heating the cleaning solution when the
temperature of the permeate water is less than 15°C. According to the manufacturer, the heated
cleaning solutions maintains the solubility of the chemicals in the solutions and enhances the
cleaning of the membrane. A detailed description of the cleaning process is in the
manufacturer's O&M Manual (Appendix B).
Data on the characteristics of the cleaning solution before, during, and after cleaning was
collected. Operational parameters were recorded before and after cleaning. The cleaning
solution data was used to characterize the cleaning solution and waste generated by cleaning of
the membranes. The operational data was collected to facilitate the calculation of the recovery of
specific flux and the loss of original specific flux.
4.3.2.1 Results of Cleaning Episodes
Table 4-3 below presents the chemical and physical characteristics of the cleaning solution.
Table 4-4 presents the results of the operational parameters collected before, during, and after the
cleaning procedure.
Table 4-3. Chemical and Physical Characteristics of Cleaning Solution
Citric Acid Cleaning Caustic Cleaning
Parameter unit Result Dup. Result Dup.
pH of Cleaning Solution Initial
2.1
2.1
12.3
12.4
pH of Cleaning Solution During Process
2.2
2.2
12.6
12.6
pH of Cleaning Solution Final
2.2
2.2
12.6
12.6
TDS of Cleaning Solution Initial
(mg/1)
4,714
12,582
TDS of Cleaning Solution During Process
(mg/1)
10,061
10,530
TDS of Cleaning Solution Final
(mg/1)
10,025
5,862
Turbidity of Cleaning Solution Initial
(NTU)
0.25
0.27
4.8
4.8
Turbidity of Cleaning Solution During Process
(NTU)
0.83
0.83
6.1
5.9
Turbidity of Cleaning Solution Final
(NTU)
0.81
0.81
0.34
0.32
Oxidant Residual Initial
(mg/1)
N/A
N/A
320
Oxidant Residual Final
(mg/1)
N/A
N/A
124
Visual Observation of Backwash Waste Initial
light yellow green
Milky
Visual Observation of Backwash Waste Final
light yellow green
gray after soak, light green after
recirculation
Table 4-4. Operational Parameter Results - Cleaning Procedure
Citric Acid Caustic Cleaning
Cleaning
Parameter Unit Time Result Result
Flow of MF Unit Prior to Cleaning
(gpm)
10:30
4.0
Pressure of MF Unit Prior to Cleaning (Feed)
(psi)
10:30
35
Pressure of MF Unit Prior to Cleaning (Retentate)
(psi)
10:30
34
Pressure of MF Unit Prior to Cleaning (Filtrate)
(psi)
10:30
5.0
Temperature of MF Unit Prior to Cleaning
(°C)
10:30
2.9
2.9
Flow of MF Unit After Cleaning
(gpm)
15:50
4.0
Pressure of MF Unit After Cleaning (Feed)
(psi)
15:50
11
Pressure of MF Unit After Cleaning (Retentate)
(psi)
15:50
10
Pressure of MF Unit After Cleaning (Filtrate)
(psi)
15:50
2.3
Temperature of MF Unit After Cleaning
(°C)
15:50
2.9
Recirculation Flow - during cleaning
(gpm)
15:50
4.0
4.0
38
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4.3.2.2 Calculation of Recovery of Specific Flux and Loss of Original Specific Flux
The following equation was used to calculate the recovery of specific flux:
Recovery of specific flux = 100 X (1- (Jsf / Js;))
where: Jsf = Specific flux (gfd/psi) at end of current run (final)
Js; = Specific flux (gfd/psi) when the system was restarted after completion of the
cleaning procedure (initial)
The specific flux prior to the start of the cleaning process was: 4.2 gfd/psi at 20°C. The specific
flux when the system was restarted after the completion of the washing procedure was: 15
gfd/psi at 20°C
Using these figures in the above equation resulted in a recovery of specific flux of 73 %.
The following equation was used calculate the loss of original specific flux:
Loss of original specific flux = 100 X (1- (Js;/ Jsi0))
where: Jsi0 = Specific flux (gfd/psi) at time zero point of membrane testing
The specific flux of the system when the membrane was placed into service in October 23, 1998,
was 17 gfd/psi at 20°C. The specific flux when the system was restarted after the completion of
the cleaning procedure was 15 gfd/psi at 20°C.
Using these figures in the above equation resulted in a loss of original specific flux of 9.0 %.
4.3.2.3 Discussion of Results
Pall recommends that cleaning be instituted when the backwashing sequence is unable to
maintain system TMP below 30 psid. The membranes were cleaned as per protocol requirements
using manufacturer's recommendations March 10, 1999.
The procedure used for chemical cleaning was defined in the operations manual and required
some manual effort. Heating of the permeate, mixing the cleaning agents into solution, and
initiation of the cleaning procedure required approximately four hours of effort by the operator.
The characterization of the citric acid cleaning wastewater indicated that the solution was acidic,
with a pH of 2.2. The citric acid cleaning waste had a turbidity of 0.81 NTU and a TDS of
10,025 mg/1. No chlorine was used in conjunction with the citric acid solution. The
caustic/chlorine cleaning waste had a pH of 12.6, a turbidity of 0.34 NTU, and a TDS of 5,862
mg/1. The total chlorine residuals of the caustic/chlorine cleaning waste was 120 mg/1. The
wastewater during the citric acid cleaning waste had a light yellow-green color. The
caustic/chlorine cleaning waste also had a light green color.
The cleaning solutions are mixed from 100% citric acid, caustic soda, and 12.5% NaOCl. Care
must be taken when handling these materials to avoid injury. No hazardous materials are present
in the cleaning solutions. The presence of hazardous materials in the wastewater would be
39
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dependent on the quality of the feed water. Depending on local regulations, the waste stream
may be able to be discharged to the sanitary sewer system.
Examination of the operational data and the recovery of specific flux showed that the cleaning
procedure did restore 73 % of the specific flux to the treatment system. This indicates that the
cleaning procedure was capable of restoring membrane performance.
The loss of original specific flux was 9.0 %. This may indicate that some irreversible
degradation of the membrane had occurred.
4.3.3 Task 3: Finished Water Quality
Results of testing for turbidity in the feed and finished water were examined to verify the stated
turbidity treatment ability. Since the feed water turbidity was consistently less than 0.1 NTU and
a turbidity challenge was not conducted this stated treatment goal was not verifiable. A graph
depicting daily logio removals for cumulative particle counts will be presented. Bacteria and
algae removal results were examined. Examination of TOC and UVA254 testing results, as well
as testing results for the inorganic parameters total alkalinity, total hardness, TDS, and TSS was
conducted. A TSS mass balance calculation will be presented. Graphs of four-hour readings for
turbidity and particle count results will be shown.
4.3.3.1 Turbidity Results and Removal
Results of testing for turbidity in the feed and finished water were examined. A summary of the
results is presented in Tables 4-5 and 4-6. A complete data table is presented in Appendix C. A
graph of this data is presented as Figure 4-3.
Table 4-5. Turbidity Analyses Results and Removal
Feed Turbidity
Daily
Sample Parameter
Feed Turbidity
(duplicate)
Filtrate Turbidity
Amount Removed
(NTU)
(NTU)
(NTU)
(NTU)
Average
0.088
0.090
0.026
0.062
Minimum
0.060
0.060
0.024
0.034
Maximum
0.14
0.13
0.032
0.095
Standard Deviation
0.018
0.018
0.0013
0.017
Confidence Interval
(0.083, 0.092)
(0.084, 0.097)
(0.026, 0.026)
(0.056, 0.068)
Table 4-6. Filtrate Turbidity Results -
Four Hour Readings
Turbidity
(NTU)
Average
0.016
Minimum
0.016
Maximum
0.026
Standard Deviation
0.0016
Confidence Interval
(0.016, 0.016)
The permeate turbidity was very low throughout the duration of the verification testing. The
inline permeate turbidimeter readings averaged 0.026 NTU; the benchtop turbidimeter readings
40
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averaged 0.042 NTU. While this may initially appear to be a significant difference, it is most
likely due to the low level of turbidity in the feed and finished water and the differences in
methodology of the two pieces of analytical equipment. The discrepancy between these two
results can be explained by differences in the analytical techniques between the online and
benchtop turbidimeter and the low level of turbidity in the permeate. The benchtop turbidimeter
uses a glass cuvette to hold the sample; this cuvette can present some optical difficulties for the
benchtop turbidimeter. The inline turbidimeter has no cuvette to present a possible interference
with the optics of the instrument. The low level of turbidity in the permeate also can create
analytical difficulties, particularly for the benchtop. Manufacturer's specifications state that
stray light interference is less than 0.02. Stray light interference approaching this level at the low
turbidity levels tested could account for the differences in the readings.
Figure 4-3 shows the results of the four-hour permeate turbidity readings. Due to problems
associated with the data logging equipment on the treatment unit the turbidity readings from run
time 596 hour to 684 hour were lost and are not available.
4.3.3.2 Particle Count Results and Removal
Particle count readings were taken on a continuous basis and recorded every 15 minutes.
Average particle count calculations were calculated from these readings. The feed water
41
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cumulative counts averaged 120 particles per ml. The finished water cumulative counts
averaged 0.54 counts per ml. The average logio removal for the cumulative counts was 2.5.
The low particle counts for each size range in the filtrate water indicated good system
performance throughout the testing period. The treatment system seems to be an effective
removal mechanism for particle removal.
Average feed water particle counts are presented in Table 4-7. Average finished water particle
counts are presented in Table 4-8. Daily average cumulative counts for feed and finished water
and the logio particle removals are presented in Table 4-9. A complete data table is presented in
Appendix C. Figures 4-4 and 4-5 depict results of four hour particle counts for feed water and
permeate. Figure 4-6 graphically depicts daily logio removals for cumulative particle counts. The
particle count readings from run time 640 hour to 732 hour were lost and are not available due to
problems associated with the data logging equipment on the treatment unit.
Table 4-7. Feed Water Particle Counts
Size
2-3 |xm
3-5|jm
5-7|xm
7-10|im
10-15|im
>15|jm
Cumulative
Average
60
37
10.5
5.8
2.2
0.75
120
Minimum
0
0
0
0
0
0
N/A
Maximum
980
680
260
480
490
93
N/A
Standard Deviation
34
23
7.2
9.7
9.7
2.0
N/A
Confidence Interval
(59,62)
(36,38)
(10,11)
(5.5, 6.2)
(1.8, 2.5)
(0.67, 0.82)
N/A
N/A = Not applicable. Statistical measurements on cumulative data do not generate meaningful data.
Note: Due to results obtained during the QA/QC task involving verification of the calibration of the particle counters the 5 |xm
readings were 20% lower than actual. Due to extremely low results in the 10 (jm and 15 (jm size range the results of the 7-10
(jm, 10-15 (jm, and >15 (jm should be considered questionable. See instrument QA/QC verification results in Section 4.5.3.
Table 4-8. Finished Water Particle Counts
Size
2-3 |xm
3-5|xm
5-7|xm
7-10|im
10-15|im
>15|jm
Cumulative
Average
0.21
0.16
0.081
0
0.045
0.044
0.54
Minimum
0
0
0
0
0
0
N/A
Maximum
72
59
20
0
10
9.5
N/A
Standard Deviation
2.2
1.6
0.63
0
0.29
0.20
N/A
Confidence Interval
(0.13,0.29
(0.10,0.22)
(0.058,0.10)
N/A1
(0.034,
0.056)
(0.037,
0.051)
N/A
N/A = Not Applicable. Statistical measurements on cumulative data do not generate meaningful data.
N/A1 = Not Applicable. Confidence interval not calculated because standard deviation equals zero.
Note: Due to results obtained during the QA/QC task involving verification of the calibration of the particle counters the above
readings were on average 16% lower than actual. See instrument QA/QC verification results in Section 4.5.3.
42
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Table 4-9. Daily Average Cumulative Particle Counts Feed and Finished Water, Logi0 Particle Removal
Date Feed Permeate Log i0 Removal
2/3/1999
120
1.4
1.9
2/4/1999
130
0.79
2.2
2/5/1999
130
0.64
2.3
2/6/1999
130
0.28
2.7
2/7/1999
120
0.36
2.5
2/8/1999
120
0.27
2.6
2/9/1999
120
0.24
2.7
2/10/1999
94
0.25
2.6
2/11/1999
85
0.24
2.6
2/12/1999
130
0.35
2.6
2/13/1999
150
0.24
2.8
2/14/1999
150
0.30
2.7
2/15/1999
140
0.17
2.9
2/16/1999
120
0.20
2.8
2/17/1999
130
0.19
2.8
2/18/1999
91
0.16
2.7
2/19/1999
80
0.17
2.7
2/20/1999
71
0.22
2.5
2/21/1999
70
0.31
2.4
2/22/1999
69
0.33
2.3
2/23/1999
67
0.32
2.3
2/24/1999
73
0.22
2.5
2/25/1999
89
0.19
2.7
2/26/1999
79
0.15
2.7
2/27/1999
71
0.46
2.2
3/3/1999
190
7.9
1.4
3/4/1999
210
1.8
2.0
3/5/1999
240
0.51
2.7
43
-------
c
D
E
o
"5)
o
o
s
ra
Q.
30
20
10
0
° ^ ^ a°? ^ <^ <$P ^ <^ <^ ^
Run Time (hours)
Feed Water 4 Hour Particle Counts vs. Time
Figure 4-4. Four Hour Feed Water Particle Counts
Permeate 4 Hour Particle Counts vs. Time
1.20
1.00
42 _ 0.80
i |
O a>
Q> O 060
o -E
t re
ra £
Q- 0.40
0.20
0.00
0 ^ ^ cf- jfp # # $ ^ <5? <$> <$> <3? ^ 15 |jm
Figure 4-5. Four Hour Permeate Particle Counts
44
-------
ns j2
1s
o O
Q£ d)
° £
o> "E
o re
-I Q.
a) a)
O) >
re ^
(B
SI 1
< E
to
a
Daily Average Log 10 Removal of Cumulative Particle Counts
vs. Date
3.00
2.50
2.00
1.50
1.00
0.50
0.00
/ if
-------
Table 4-11. Finished Water Quality
Parameter
Total
Total
Total
Alkalinity Hardness
TDS
TSS
Coliforms
HPC
TOC
UVA
Algae
(mg/1)
(mg/1)
(mg/1)
(mg/1)
(cfu/100 ml) (cfu/100 ml)
(mg/1)
(cm -1)
(cells/ml)
Average
40
98
213
0.55
0
4
4.02
0.020
<8
Minimum
36
92
178
<0.05
0
0
3.21
0.020
<8
Maximum
43
110
284
1.15
0
12
4.86
0.020
<8
Std. Dev.
2.6
7.5
43.1
0.64
0
5
0.78
0.000
0
Confidence
(38,42)
(91.4,
(175,251)
(-0.07, 1.17)
N/A
(0, 8)
(3.25,
N/A
N/A
Interval
104.6)
4.78)
N/A = Not Applicable because standard deviation = 0
Note: Calculated averages for less than results (<) utilize half of the Level of Detection (0.05 mg/1) or 0.025 mg/1 in these
calculations. (Gilbert, 1987).
The following observations were made after examination of the results of feed and finished water
testing.
Reductions were seen in HPC. HPC averaged 11 colony forming units (cfu)/100ml in the feed
water. Permeate HPC concentrations were 4 cfu/lOOml on average. The presence of HPC in the
permeate may have been due to inadequate disinfection of the Tygon tubing used for water
sampling and to the lid design of the RF tank which permitted some environmental contaminants
to intrude into the permeate side of the system. Pall reports that the RF tank has been redesigned
with a protective lid.
Algae concentrations were reduced. Feed water contained 19 cells/ml on average. No algae was
detected in the permeate in the four samples analyzed during the verification testing.
No improvement in TSS was observed; in fact analyses indicated that the permeate TSS was
slightly higher than the feed TSS. The feed TSS was 0.21 mg/1 on average; the permeate TSS
averaged 0.56 mg/1. Possible explanations for TSS increase in field studies are particulate
shedding from the membranes and analytical error due to methodologies in the TSS analyses. As
previously noted, however, the Pall WPM-1 MF system uses membranes that are manufactured
from a polyvinylidenefluoride polymer. The manufacturer reports that there has never been any
evidence of the polyvinylidenefluoride polymer membranes shedding mass into the permeate.
The most likely explanation for the increase of TSS in the permeate involve the analyses
themselves. The results could be a function of the relatively low levels of TSS in the feed water.
The laboratory uses Standard Method 2540 D. According to the Standard Methods in the
Precision Section of the method, the standard deviation at 15 mg/1 was 5.2 mg/1, a coefficient of
variation of 33%. At higher concentrations, the coefficient of variation decreases, 10 % at 242
mg/1. (APHA et al., 1992). There is a relative lack of precision with Standard Method 2540 D at
low levels and low levels were seen in the testing. The laboratory was contacted and reported
that at the low levels tested the method is very poor at generating meaningful results. It should
also be noted that an examination of the TSS results for the feed water and permeate indicate that
the 95% confidence interval for each actually overlap.
The membrane pilot unit had little or no effect on the total alkalinity, TDS, and total hardness for
the conditions tested. This was not unexpected since these parameters are not present in the
water as solid constituents and are not amenable to reduction by physical straining.
46
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TOC and UVA254 were not well removed from the feed water. The values of UVA254 in both the
feed water and permeate were very similar as the respective confidence intervals overlapped and
average values were nearly identical. These results suggested that the microfiltration membrane
did not affect dissolved organic chemicals.
The TOC values were higher in the permeate than in the feed water by approximately 2 mg/L.
The TOC values were consistently higher in each of the four samples analyzed. These same
samples were also analyzed for dissolved organic carbon (DOC) and showed that most (>90%)
of the TOC was from the DOC (PWSA laboratory report in Appendix H). Considering that the
UVA254 values were nearly identical between the feed water and permeate, the TOC/DOC is
most likely from dissolved organic chemicals not absorbing at the 254-nanometer wavelength.
There are very few sources of DOC that could account for the observed increase in TOC.
Biological growth in the plumbing systems of the treatment system is the most likely source of
DOC in the permeate. The membrane package plant, which included plumbing components and
the membrane module, was on line at the test site for one year prior to the ETV testing. The
plumbing components of the package plant were made of polyvinylchloride (PVC). Also, the
membrane module cleaning cycle was composed of citric acid soak and caustic/chlorine (0.1N
NaOH solution) rinse and was not used on the permeate line from the module and therefore
would not have resulted in any major disinfection in the permeate sample line. Bacterial growth
may have occurred throughout the plumbing system during the year prior to ETV testing and the
resulting bio-film may have contributed to the DOC, although no biofilm growth on the
plumbing or biolfilm sloughing was observed during visual inspections. Without additional
research, which is outside of this verification study, the actual source of DOC is not known, but
considering the circumstances of testing, unexpected bacterial growth prior to this testing could
account for the observed increase in the TOC/DOC. Total coliform reduction could not be
demonstrated due to the absence of total coliforms in the feed water and permeate throughout the
test.
Temperature of the feed water was fairly stable during the thirty day testing from a high of 4.5°C
to a low of 3.4°C. The average temperature was 3.8°C.
4.3.3.4 Backwash Wastewater Testing Results
Daily and weekly testing was conducted on the backwash wastewater. The results of the testing
are listed in Table 4-12 and Table 4-13. A complete data table is presented in Appendix C.
Table 4-12. Daily Backwash Wastewater Testing Results - Summary
Parameter
Turbidity Turbidity (dup) Chlorine Residual
(NTU) (NTU) (mg/1)
Chlorine Residual (dup)
(mg/1)
Average
0.74
0.79
3.6
3.6
Minimum
0.13
0.12
2.1
2.1
Maximum
3.4
3.5
6.0
5.2
Standard Deviation
0.68
0.82
1.1
1.1
Confidence Interval
(0.57,0.91)
(0.50, 1.1)
(3.2, 4.0)
(3.2, 4.0)
47
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Table 4-13. Weekly Backwash Wastewater Testing Results
Parameter
TSS
Total Coliforms
HPC
(mg/1)
(cfu/100 ml)
(cfu/100 ml)
Average
0.22
0
50
Minimum
<0.05
0
5
Maximum
0.60
0
130
Standard Deviation
0.23
0
68
Confidence Interval
(0.013,0.42)
N/A
(-27, 127)
N/A = Not Applicable because standard deviation = 0
Note: Calculated averages for less than results (<) utilize half of the Level of Detection (0.05 mg/1) or 0.025 mg/1 in these
calculations. (Gilbert, 1987).
The turbidity of the backwash waste was quite variable but averaged 0.74 NTU. The chlorine
residual was relatively consistent averaging 3.6 mg/1. TSS content in the backwash waste was
somewhat variable; but the backwash procedure appeared to be removing some particulate
material. Total coliforms were absent in the backwash waste but HPC was observed.
4.3.3.5 Total Suspended Solids Mass Balance
The protocol requires that a calculation of the mass balance of TSS be performed. The
calculation was to be done from the amount of suspended solids entering the treatment system,
the amount in the finished water, and the amount in the backwash waste. The difference in these
two results would equal the portion of the TSS which will not be removed by backwashing and
accumulates on the membrane. The majority of this accumulated material, presumably, would be
dissolved and removed by chemical cleaning.
As previously mentioned, the permeate TSS was slightly higher than the feed TSS. A discussed
in Section 4.3.3.3 these results are possibly due to the relatively low levels of TSS in the feed
water and analytical limitations. Due to the nature of the analytical results the TSS mass balance
can not be calculated.
4.3.4 Task 4: Reporting of Maximum Membrane Pore Size
The manufacturer reports that the membrane used during the verification testing has a maximum
pore size of 0.3 |im and that 90% of the pores in their membrane are equal to or less than 0.19
|im. The manufacturer reports that these results were generated through the use of ASTM
Method F316-86 (Test Method for Pore Size Characterization of Membrane Filters for Use with
Aerospace Fluids - Version 86) and Scanning Electron Microscopy photomicrograph analysis.
This is provided for informational purposes only. These results are provided by the equipment
manufacturer and were not verified during the ETV testing. Appendix I contains an
informational brochure with a graphic representation of the above information.
4.3.5 Task 5: Membrane Integrity Testing
The methods employed for detecting a compromised membrane during the ETV test were the air
pressure hold test, turbidity reduction monitoring, and particle count reduction monitoring. These
48
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tests were run on an intact membrane and one that had been intentionally compromised. Testing
was conducted March 11, 1999 after the completion of the chemical cleaning, as is standard
procedure for the manufacturer. A complete data table is presented in Appendix C. The
following is a discussion of the membrane integrity testing results.
4.3.5.1 Air Pressure Hold Test Results
The membrane vessel with the intact membrane was removed from the treatment unit and the
filtrate side was drained. The membrane itself was fully wetted (i.e. membrane pores were filled
with water). The membrane was air pressurized up to 16 psi. The filtrate side was sealed and
the pressure decline rate was monitored using an air pressure gauge.
At time zero the air pressure was 16.1 psi, after three minutes the air pressure was 15.9 psi. At
five minutes the air pressure inside the membrane was 15.8 psi, this demonstrated that the
membrane was intact. (An intact membrane would be expected to lose no more than 1 psi every
five minutes.)
Air pressure loss was also compared to the loss that was obtained when testing a compromised
membrane. The membrane was intentionally compromised by removing the membrane vessel,
exposing the fibers themselves, and severing a fiber.
At time zero the air pressure was 18.5 psi, after two minutes the air pressure was 7.3 psi. At five
minutes the air pressure inside the membrane was zero psi. This demonstrated that the membrane
was compromised.
4.3.5.2 Turbidity Reduction Monitoring
Turbidity of feed and filtrate water was monitored. An intact membrane would be expected to
show a 90% reduction in turbidity from feed to filtrate. Due to the high quality of the feed water,
the average feed turbidity was 0.088 NTU, showing a 90% reduction, 0.0088 NTU, was beyond
the capability of the turbidimeters. Filtrate turbidity between an intact and a compromised
membrane was compared. An increase of 100 % was used as an indication of a compromised
membrane. The turbidity in the filtrate in the 15 hours before the membrane was compromised
averaged 0.033 NTU. The turbidity of the filtrate in the two hours after the membrane was
compromised was 0.14 NTU. The permeate turbidity was somewhat variable during the run with
the compromised membrane. It fluctuated from a maximum of 0.36 NTU to a minimum of
0.016 NTU.
Turbidity reduction monitoring between feed and finished water was not possible due to the low
feed water turbidity level. The filtrate turbidity produced by an intact membrane was
significantly lower than the filtrate turbidity produced by a compromised membrane.
Comparison of the filtrate turbidity between intact and compromised membranes did detect a
compromised membrane. Given the variability in permeate turbidity during the run with the
compromised membrane care should be taken in using this method for detecting a compromised
membrane.
49
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4.3.5.3 Particle Count Reduction Monitoring
Particle count reductions from source to finished water of 99.9% could indicate an intact
membrane. The average cumulative feed water particle counts were 120 total counts per ml,
showing a 99.9% reduction would equal total cumulative counts of 0.12 counts per ml. Average
permeate particle counts throughout the verification testing were 0.54 counts per ml. Therefore a
99.9% reduction could not be used as an indication of an intact membrane. Differences between
filtrate particle counts from an intact and a compromised membrane were compared. An
increase of 100% was used as an indication of a compromised membrane.
The average cumulative particle count of the filtrate in the 15 hours before the membrane was
compromised was 0.52 counts/ml. The average cumulative particle count of the filtrate in the two
hours after the membrane was compromised was 82 counts/ml. The permeate particle counts
were somewhat variable during the run with the compromised membrane. They fluctuated from
a maximum of 640 counts per ml to a minimum of zero counts per ml. In fact, only two of eight
counts were in excess of 0.75 count per ml. This variability of the particle count readings raises
some question as to the reliability of using particle counts as an indication of a compromised
membrane. Care should be taken in relying on this method solely to detect a compromised
membrane.
4.3.6 Task 6: Giardia and Cryptosporidium Removal
The purpose of this task was to demonstrate the treatment unit's ability to provide a minimum 3
logio removal from feed water to plant effluent of Giardia cysts and a 2 logio Cryptosporidium
oocysts. The Giardia and Cryptosporidium challenge took place on February 5, 1999. The
system operated at a manufacturer recommended flux of 120 gfd at 20°C (77 gfd at 3.6°C) and an
average specific flux of 5.0 gfd/psi at 20°C (50 l/m2/h/b at 20°C) during the Giardia and
Cryptosporidium removal challenge testing.
4.3.6.1 Feed Water Concentrations
During the Giardia and Cryptosporidium removal challenge testing, the feed water had a pH of
7.7, a turbidity of 0.10 NTU, and a temperature of 3.6°C. Based on the results of hemocytometer
replicate counts, a total of 10,768,000 Giardia cysts and 104,548,000 Cryptosporidium oocysts
were added to 50 gallons of feed water in the feed water reservoir. This resulted in a
concentration of 215,360 Giardia cysts per gallon and 2,090,960 Cryptosporidium oocysts per
gallon in the feed water. The stock suspension of feed water and the cysts and oocysts was
constantly mixed using a drum mixer. A diaphragm pump was used to add the stock suspension
to the Pall WPM-1 unit. The pump was operated at about 0.85 gpm, (3.2 liter per minute) and
was capable of overcoming the pressure in the feed water line of the pilot unit. The feed water
from the feed water reservoir was fed to the system for approximately 60 minutes.
As a QC check of the hemocytometer counts, a composite of the feed water was created from
five two-ml aliquots taken at five to ten minute intervals. Microscopic examination of the results
of this composite indicated 11,780,000 Giardia cysts and 101,080,000 Cryptosporidium oocysts.
These results were 9.4 % greater and 3.3% less, respectively, than the results obtained from the
50
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hemocytometer counts. The hemocytometer counts were used to calculate the initial
concentration of the feed water per EPA protocols and due to the uncertain nature of sampling
and mixing of the suspension, which could render the composite sample results questionable.
The feed water results of the replicate hemocytometer counts are presented in Table 4-14. The
microscopic examination results of the composite sample are presented in Table 4-15. Bench
data sheets and report from the laboratory are enclosed in Appendix H.
Table 4-14. Giardia and Cryptosporidium Stock Suspension Results by Hemocytometer Counts
Giardia Cysts Cryptosporidium Oocysts
Average count (oocysts or cysts/0.0001ml)
134
1,306
Standard Deviation
12
8
Confidence Interval
(122, 146)
(1,298, 1,314)
Total cysts and oocysts added to feed
10,768,000
104,548,000
water reservoir (8 mis of stock suspension)
Feed Water Amount Confidence Interval
(9,760,000, 11,680,000)
(103,840,000,105,120,000)
Table 4-15. Giardia and Cryptosporidium Stock Suspension Results by Microscopic Examination
Giardia Cysts Cryptosporidium Oocysts
Presumptive count (oocysts or cysts/ml) 62 532
Total cysts and oocysts added to feed 11,780,000 101,080,000
water reservoir
4.3.6.2 Permeate Concentrations
No Giardia cysts or Cryptosporidium oocysts were identified in the permeate as shown by the
absence of cysts and oocysts on the 1 |im yarn wound capture filter. These results demonstrated
a 5.8 logio removal of Giardia cysts and a 6.8 logio removal of Cryptosporidium oocysts using
the hemocytometer counts of the feed water. During the Giardia and Cryptosporidium removal
challenge testing, the filtrate had a turbidity of 0.026 NTU and an average cumulative particle
counts of 0.65 counts/ml.
The logio removal of Giardia cysts or Cryptosporidium oocysts was calculated by first dividing
the amount of permeate sampled by the total amount of permeate filtered by the system. In this
case, one gallon per minute was filtered through the sampling filter compared to four gallons per
minute of permeate produced by the treatment system. This result was applied to the total
amount of cysts added to the treatment system and used to calculate the total amount of cysts
which could have been trapped on the sampling filter. This number was converted to its logio
equivalent. The percent recovery of the test method at the PWSA laboratory is 25%, this means
that the lowest number of cyst or oocysts that could be detected is four. That is, if four cysts or
oocysts were in the permeate one of them would be detected. This number, four, was also
converted to its logio equivalent. The final log removal calculation was made by subtracting the
logio of the number of cysts added to the sampling filter less the logio of the number of cysts
trapped on the sampling filter, in this case zero, and then subtracting the logio of the number
four. Table 4-16 presents the concentrations and the logio removal calculations of the Giardia
cysts and Cryptosporidium oocysts.
51
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Table 4-16. Giardia and Cryptosporidium Challenge Logi0Removal Calculation
Giardia Cyst Removal Cryptosporidium Oocyst Removal
Cysts/oocysts in Feed Reservoir (from Table 4-14)
10,768,000
104,548,000
Cysts/oocysts Added to Capture Filter (The total number of
cysts/oocysts in Feed Reservoir multiplied by 25% because the
system was pumping at 4gpm and sampled at Igpm. Effectively,
only 25% of the total cysts/oocysts added could have been
detected on the capture filter.)
2,692,000
26,140,000
Log10 of Cysts/oocysts Added to Capture Filter
6.4
7.4
Log10 of Method Recovery (PWSA laboratory method recovery
is 25%, i.e. 1 in 4.)
0.60
0.60
Log10 Removal (Difference ofLogI0 of Cysts/oocysts Added to
Capture Filter and LogI0 of Method Recovery)
5.8
6.8
4.3.6.3 Backwash Examination
Examination of the wastewater was conducted to assure that the protozoans were added to the
membrane system, the organisms were removed by the membrane and that the backwashing
procedure was capable of removing the protozoans from the membrane system. Five hundred ml
of the backwash waste was collected and examined. Both Giardia cysts and Cryptosporidium
oocysts were observed in the sample. Quantification of the numbers of each organism in the
sample was not done.
4.3.6.4 Operational and Analytical Data Tables
The operation of the treatment system was monitored during the challenge testing. Pressure
readings and flow rates were recorded. Results of these readings are presented in Tables 4-17
and 4-18. Turbidity and particle count readings were taken during the challenge testing.
Samples for feed water turbidity and particle counts were collected upstream of the point where
the Giardia cysts and Cryptosporidium oocysts were added to the feed water stream. Results of
the turbidity and particle count readings are presented in Tables 4-19, 4-20, and 4-21. Backwash
of the system was delayed, as per protocol requirements, until after the challenge testing was
completed. Samples of backwash water before and after the challenge were collected and
analyzed. Results of these analyses are presented in Table 4-22.
Table 4-17. Pressure Readings and Calculations During Giardia and Cryptosporidium Removal Testing
Feed Pressure Retentate Pressure Filtrate Pressure Transmembrane
Pressure
Date Time (psi) (psi) (psi) (psi)
02/05/99 10:24 29 26 3 24
02/05/99 13:20 28 30 3 25
52
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Table 4-18. Specific Flux During Giardia and Cryptosporidium Removal Testing
Specific Flux
Date Time (gfd/psi (aj20°C)
02/05/99 10:24 5.2
02/05/99 13:20 4.8
Table 4-19. Turbidity Analyses Results and Removal During Giardia and Cryptosporidium Removal Testing
Feed Filtrate
Turbidity Turbidity Turbidity Amount Removed
(duplicate)
Date Tune (NTU) (NTU) (NTU) (NTU)
02/05/99 10:50 0.10 0.11 0.026 0.074
02/05/99 12|45 009
Note: Feed water turbidity sampled prior to injection of challenge feed solution.
Table 4-20. Feed Water Particle Counts 2/5/1999
Size
2-3 pm 3-5)xm 5-7 pm 7-10)jm 10-15)jm >15)xm Cumulative
Average
71
42
12
6.5
2.2
0.68
130
Minimum
0.17
0.12
0.090
0.090
0.24
0.060
N/A
Maximum
130
77
20
10
4.6
2.1
N/A
Std Dev
21
12
3.6
1.9
0.84
0.32
N/A
Confidence
(67, 76)
(39,44)
(11,12)
(6.0, 6.9)
(2.1,2.4)
(0.61, 0.74)
N/A
Interval
N/A = Not Applicable. Statistical measurements on cumulative data do not generate meaningful data.
Note: Feed water particle counts sampled prior to injection of challenge feed solution.
Table 4-21. Finished Water Particle Counts 2/5/1999
Size
2-3 pm 3-5)xm 5-7 pm 7-10)jm 10-15)jm >15)xm Cumulative
Average
0.20
0.22
0.11
0.0
0.064
0.049
0.64
Minimum
0.0
0.0
0.0
0.0
0.0
0.0
N/A1
Maximum
8.3
7.3
4.2
0.0
1.9
0.97
N/A1
Std Dev
0.97
0.82
0.44
0.0
0.20
0.10
N/A1
Confidence
(0.0060,0.40) (0.054,0.38)
(0.024, 0.20)
N/A
(0.025,0.10)
(0.028, 0.070)
N/A1
Interval
N/A = Not applicable because standard deviation = 0.
N/A1 = Not Applicable. Statistical measurements on cumulative data do not generate meaningful data.
Table 4-22. Daily Backwash Wastewater Testing Results During Giardia and Cryptosporidium Removal Testing
Turbidity Turbidity (dup) Chlorine Residual Chlorine Residual (dup)
Date Time (NTU) (NTU) (mg/1) (mg/1)
02/05/99 11:15 1.66 1.67 2.20 2.40
02/05/99 12:45 0.25
Testing of the feed, finished and backwash water for Total Alkalinity, Total Hardness, TDS,
TSS, Total Coliforms, HPC, TOC, UVA was not conducted during the challenge testing
procedure.
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4.3.6.5 Discussion of Results
No Giardia cysts or Cryptosporidium oocysts were observed in the permeate. The membranes
appeared to successfully remove all of the Giardia cysts and Cryptosporidium oocysts
introduced into the treatment system. Since the percent recovery of the analytical method is 25%
there is a slight possibility that some cysts or oocysts passed through the membrane and were not
identified during analysis. Nevertheless, the treatment system provided 5.8 logio removal of
Giardia cysts and a 6.8 logio removal of Cryptosporidium oocysts. These results indicate that the
treatment system would be capable of successfully complying with the current protozoan
removal requirements of the SWTR and ESWTR, if used on this source water. The current
provisions are 3 logio removal of Giardia cysts and 2 logio removal of Cryptosporidium oocysts
as stated in Section 3.1.1.2.
The logio removals of the Giardia cysts and Cryptosporidium oocysts were limited by the
amount of the parasites which were present in the stock feed solution, the percentage of the
permeate that could be sampled, and the percent recovery of the analytical methodology. Higher
feed concentrations, percentage of permeate examined and percent recovery of the analytical
methods may yield higher logio removals.
4.4 Equipment Characteristics Results
The qualitative, quantitative and cost factors of the tested equipment were identified during
verification testing, in so far as possible. The results of these three factors are limited due to the
relatively short duration of the testing cycle.
4.4.1 Qualitative Factors
Qualitative factors that were examined during the verification testing were the susceptibility of
the equipment to changes in environmental conditions, operational reliability, and equipment
safety.
4.4.1.1 Susceptibility to Changes in Environmental Conditions
Changes in environmental conditions that cause degradation in feed water quality can have an
impact on the treatment system. The short duration of the testing cycle and the stable nature of
the feed water minimized the opportunity for significant changes in environmental conditions.
As previously stated the reservoir water was treated (coagulated, flocculated, settled, filtered, and
disinfected) surface water that had been pumped from PWSA's Aspinwall treatment plant. The
fact that the feed water was finished drinking water stored in an open reservoir limited the
opportunity for significant changes in feed water quality. No environmental upsets significant
enough to affect feed water quality occurred during testing. Since the treatment unit was housed
in the pumping station and is not exposed to the elements, opportunities for environmental upsets
were limited.
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4.4.1.2 Operational Reliability
During the verification test the unit operated in the automatic mode. A power failure occurred at
the pumping station on March 3 and caused the treatment system to shut down. After the system
was reset by Pall personnel, the treatment unit was restarted.
Manual operation was required for chemical cleaning of the system and to refill the container of
sodium hypochlorite used to supply chlorine to the backwash water. Data was transmitted daily
to Pall headquarters. After examination of the data, necessary operational changes could be
made remotely from Pall's offices. Not all of the operational parameters could be changed from
the remote location. No significant operational changes were necessary throughout the
verification testing.
4.4.1.3 Equipment Safety
Evaluation of equipment safety was conducted as part of the verification testing. Evaluation of
the safety of the treatment system was done by examination of the components of the system and
identification of hazards associated with these components. A judgement as to the safety of the
treatment system was made from these evaluations.
There are safety hazards associated with high voltage electrical service and pressurized water.
The electrical service was connected according to local code requirements and did not represent
an unusual safety risk. The water pressure inside the treatment system was relatively low and
did not represent an unusual safety risk.
The sodium hypochlorite used for membrane backwashing created a safety concern. The use of
appropriate personal protective equipment (PPE) minimizes the risk of exposure when handling
the chemical. The prompt and proper clean up of spills also minimizes the hazards associated
with this chemical.
The cleaning chemicals, citric acid and sodium hydroxide are hazardous chemicals. The use of
appropriate PPE minimizes the risk of exposure to this substance. The prompt and proper clean
up of spills minimizes the hazards associated with this chemical.
No injuries or accidents occurred during the testing.
4.4.2 Quantitative Factors
Quantitative factors that were examined during verification testing were power supply
requirements, consumable requirements, waste disposal technique, and length of operating cycle.
Cost factors for the above items are discussed where applicable. It is important to note that the
figures discussed here are for the Pall Corporation WPM-1 Pilot System operating at 77 gfd at
3.8°C (120 gfd at 20°C). Costs will vary if the system is operated at different flux rates.
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4.4.2.1 Power Supply Requirements
The unit was operated with 208 - 240 VAC, single phase, 15 Amp current as required by the
O&M manual. Daily power consumption of the treatment unit was determined by reading a
dedicated electric meter. The electric meter was installed by a certified electrician according to
the local electric code.
It became apparent after the first days that the meter was not registering electric usage. It was
determined that the electric meter was not functioning. Due to the short duration of the study
and the inability of the electric contractor to respond in a timely manner it was not possible to
change the meter before the end of the study.
4.4.2.2 Consumable Requirements
Consumable commodities included sodium hypochlorite and the cleaning chemicals, citric acid
and sodium hydroxide. Sodium hypochlorite was added to the permeate used for backwashing.
The total chlorine residual in the backwash waste was 3.6 mg/1. This level of chlorine residual
required approximately 1/2 gallon of 12.5% sodium hypochlorite per month. The chemical
cleaning episode requires 8 lbs. (3600 g) of citric acid and about 1.7 lbs (760 g) sodium
hydroxide. Each of these chemicals is added to approximately 50 gallons of permeate.
4.4.2.3 Waste Disposal
The wastes generated by the treatment system were backwash water and the chemical cleaning
wastes. The Giardia and Cryptosporidium challenge testing also generated wastes during the
verification testing. All of these wastes were disposed of to an existing catch basin that was
connected to PWSA's sewerage system. The unit produced approximately 220 gpd of backwash
water during verification testing.
The characterization of the citric acid cleaning wastewater indicated that the solution was acidic,
with a pH of 2.2. The citric acid cleaning waste had a turbidity of 0.81 NTU and a TDS of
10,025 mg/1. No chlorine was used in conjunction with the citric acid solution. The
caustic/chlorine cleaning waste had a pH of 12.6, a turbidity of 0.34 NTU, and a TDS of 5,862
mg/1. The total chlorine residual of the caustic/chlorine cleaning waste was 120 mg/1. The
wastewater during the citric acid cleaning had a light yellow-green color.
The backwash waste was finished water, residual chlorine and solids removed from the
membrane; it required no treatment prior to discharge to the sewers. The average concentration
of TSS in the backwash waste was 0.21 mg/1. The range of TSS concentration was from less
than 0.050 mg/1 to 0.60 mg/1. The chlorine concentration in the backwash wastewater averaged
3.6 mg/1 and ranged from 2.2 mg/1 to 6.0 mg/1.
A complete presentation of the backwash wastewater data is included in Appendix C.
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The microbial challenge utilized formalin fixed Giardia cysts and Cryptosporidium oocysts. The
backwash waste from the challenge test was collected, chlorinated, and stored for 3 days prior to
discharge.
4.4.2.4 Length of Operating Cycle
There were two "operating cycles" to be considered; the filtration cycle and the interval between
chemical cleaning. The lengths of these operating cycles are site specific and determined by the
manufacturer after evaluation of the feed water quality. These cycle lengths are easily field
adjustable if necessary; no adjustments were required for this verification.
The filtration cycle is the length of time between system backwashes. The interval between
backwashes is made based on the maintenance of flux. That is, if the backwash is not able to
maintain flux at a particular level, the frequency of backwashing is increased. The filtration
cycle was 30 minutes for the verification study. The unit under went a system backwash twice
per hour. One of the backwashes was a RF cycle and the other was a RF/AS cycle.
The interval between chemical cleaning is estimated to be 30 days. Pall recommends that
cleaning be done when the RF and RF/AS cycles are unable to maintain a TMP of less than 30
psid. The unit had undergone chemical cleaning 13 days prior to the start of the verification
testing. The TMP reached 30 psid 5 days after the conclusion of the 30 day testing.
4.5 QA/QC Results
The daily, bi-weekly, initial, and the analytical laboratory QA/QC verification results are
presented below.
4.5.1 Daily QA/QC Results
Daily readings for the inline turbidimeter flow rate and readout and inline particle counter flow
rate QA/QC results were taken and recorded.
The inline feed water turbidimeter flow rate averaged 399 ml/minute. The flow rate was verified
volumetrically using a graduated cylinder and stop watch. The maximum rate measured, during
the testing was 660 ml/minute; the minimum was 50 ml/minute. This occurred on the first day
and after conferring with Pall representatives to verify that the instrument did not have
specialized operating parameters, the flow rate was adjusted to within its normal operating range.
The acceptable range of flows as specified by the manufacturer is 250 ml/minute to 750
ml/minute. The flow rate required adjustment on 11 of the 30 days of testing.
The readout from the inline turbidimeter averaged 0.055 NTU; the average from the benchtop
turbidimeter was 0.088 NTU. The discrepancy between these two results can be explained by
differences in the analytical techniques between the online and benchtop turbidimeter and the
low level of turbidity in the feed water. The benchtop turbidimeter uses a glass cuvette to hold
the sample; this cuvette can present some optical difficulties for the benchtop turbidimeter. The
online turbidimeter has no cuvette to present a possible interference with the optics of the
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instalment. The low level of turbidity in the feed water also can create analytical difficulties,
particularly for the benchtop. Manufacturer's specifications state that stray light interference is
less than 0.02. Stray light interference approaching this level at the low turbidity levels tested
could account for the differences in the readings.
The inline filtrate turbidimeter flow rate averaged 400 ml/minute. To determine the flow rate of
the inline filtrate turbidimeter, the flow was measured using a graduated cylinder and stop watch.
The maximum rate measured during the testing was 650 ml/minute; the minimum was 50
ml/minute. This occurred on the first day and after conferring with Pall representatives to verify
that the instrument did not have specialized operating parameters, the flow rate was adjusted to
within its normal operating range. The acceptable range of flows as specified by the
manufacturer is 250 ml/minute to 750 ml/minute. The flow rate required adjustment on 4 of the
30 days of testing.
The readout from the inline turbidimeter averaged 0.026 NTU; the average from the benchtop
turbidimeter was 0.042 NTU. The discrepancy between these two results can be explained by
differences in the analytical techniques between the online and benchtop turbidimeter and the
low level of turbidity in the permeate. The benchtop turbidimeter uses a glass cuvette to hold the
sample; this cuvette can present some optical difficulties for the benchtop turbidimeter. The
online turbidimeter has no cuvette to present a possible interference with the optics of the
instrument. The low level of turbidity in the permeate also can create analytical difficulties,
particularly for the benchtop. Manufacturer's specifications state that stray light interference is
less than 0.02. Stray light interference approaching this level at the low turbidity levels tested
could account for the differences in the readings.
The feed water particle counter flow rate averaged 99.5 ml/minute. To determine the flow rate of
the inline filtrate turbidimeter, the flow was measured using a graduated cylinder and stop watch.
The maximum flow rate measured was 104 ml/minute; the minimum was 94 ml/minute. The
target flow rate specified by the manufacturer is 100 ml/minute. Efforts were made to keep the
flow rate between 95 ml/minute to 105 ml/minute.
Adjustments to the flow rate were required two times during the verification study.
The finished water particle counter flow rate averaged 97.9 ml/minute. The flow rate was
verified using a graduated cylinder and stop watch. The maximum flow rate measured was 102
ml/minute; the minimum was 95 ml/minute. The target flow rate specified by the manufacturer
is 100 ml/minute. Efforts were made to keep the flow rate between 95 ml/minute to 105
ml/minute. Adjustments to the flow rate were required one time during the verification study.
4.5.2 Bi-weekly QA/QC Verification Results
Every two weeks checks were made on the inline flow meters; the meters were cleaned out if
necessary and the flow readouts were verified.
The flow meters were inspected. Clean out of the meters was not necessary due to the high
quality of the feed and finished water.
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The flow meter readout was verified during the testing. The readout was compared to the results
obtained from the actual amount measured using a graduated cylinder and stopwatch. The
acceptable range of accuracy for the feed, finished and backwash meters was +/- 10%. The
permeate water meter readout averaged 2.5 % higher than actual according to the results
obtained during the flow verification. The retentate water meter readout averaged 3.8 % lower
than actual according to the results obtained during the flow verification. The treatment system
did not have a backwash meter.
4.5.3 Results of QA/QC Verifications at the Start of Each Testing Period
At the start of the testing period the inline turbidimeter was cleaned out and recalibrated, the
pressure gauges/transmitters readouts were verified, the tubing was inspected, and the inline
particle counter calibration was checked.
The inline turbidimeter reservoir was drained and cleaned and the unit was recalibrated
according to manufacturer's recommendations. No corrective action was required as a result of
these activities.
The feed water and permeate pressure gauges were checked prior to the start of testing. (The
manufacturer was unable to remove the retentate pressure gauge from the treatment unit.) Dead
weights of 5,10, 15, 20, and 30 pounds were used. The feed water pressure gauge averaged 4.1
psi, 9.0 psi, 14.0 psi, 18.9 psi, and 28.9 psi when tested with the above weights. The permeate
pressure gauge averaged 4.2 psi, 9.8 psi, 14.2 psi, 19.8 psi, and 29.5 psi when tested with the
above weights. These results were considered satisfactory.
The tubing used on the treatment system was inspected for cracks and flaws which could have
caused unexpected failure prior to the initiation of testing. The tubing was in good condition and
replacement was not necessary.
The calibration of the inline particle counters was checked. The cocktail of microspheres was
prepared to give an initial concentration of 2,000 particles/ml for each of the 5 |im, 10 |im, and
15 |im sized particles.
The feed water particle counter showed an average response for the 5 |im size of 1,600
counts/ml; the 10 |im size showed an average response of 1,200 counts/ ml; the 15 |im size
showed an average response of 860 counts/ ml. This corresponds to a difference of 20%, 64%,
and 132% respectively in particle counts. These results were outside of the generally recognized
range of +/- 10 %. The manufacturer of the particle counters was contacted to determine what
corrective action could be utilized to rectify this low response. The technical representative
indicated that unit would have to have been returned to the factory for recalibration. The
representative indicated that the lead time for this service was in excess of one month. Due to
the short duration of the testing schedule and the treatment system manufacturer's time
constraints this was not a feasible option. The technical representative indicated that the
calibration procedure consisted of adjusting the "threshold" of the unit. This consists of
adjusting the output of the unit to match the concentration of the standard being analyzed. The
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representative indicated that this "threshold" adjustment is analogous to increasing the readout of
the unit by the percent differences obtained during the calibration check procedure. The percent
difference for the 5 |im standard used was 20%. The readings for 5 |im feed water particle
counts obtained during the verification testing should be increased by 20% to account for the low
response of the 5 |im size range of the feed water particle counter. Due to extremely low results
in the 10 |im and 15 |im size range the reliability of the 7-10 |im, 10-15 |im, and >15 |im particle
counts should be considered questionable.
The finished water particle counter showed an average response for the 5 |im size of 1,800
counts/ml; the 10 |im size showed an average response of 1,700 counts/ ml; the 15 |im size
showed an average response of 1,600 counts/ ml. This corresponds to a difference of 10%, 15%,
and 22% respectively in particle counts. The 10 |im and 15 |im results were outside of the
generally recognized range of +/- 10 %. The manufacturer of the particle counters was contacted
as described above. The average percent difference for the 5 |im, 10 |im, and 15 jam standards
was 16%). The readings for finished water particle counts obtained during the verification testing
should be increased by 16% to account for the low response of the finished water particle counts
The particle counters used during the testing were Met-One PCX models. The units had
capabilities of measuring particles as small as 2 |im and a coincidence error of less than 10 %.
Particle counter model, serial number, calibration certificate, and calculation of coincidence error
are included in Appendix J.
4.5.4 Analytical Laboratory QA/QC
Samples for analyses conducted on feed and finished water are listed in Table 4-1. QA/QC
procedures are based on Standard Methods, 18th Ed., (APHA, 1992) and Methods for Chemical
Analysis of Water and Wastes, (EPA 1979).
The laboratory participated in the ICR laboratory approval program sponsored by the EPA. The
PWSA's QA/QC results from the ICR program as they relate to microbial testing are attached in
Appendix H. The analyses conducted as part of this program include samples with unknown
amounts Giardia cysts and Cryptosporidium oocysts. These samples were analyzed and the
results submitted to EPA for evaluation. These blind QA/QC samples were analyzed for 18
months as part of the ICR lab program and served as the QA/QC component of the microbial
testing for the verification testing. Results of these QA/QC samples indicate that the controls in
place were adequate to render the data obtained from the challenge testing acceptable.
Calibration results of the analytical instrumentation used to conduct the analyses listed in Table
4-1 on finished water is recorded and kept on file at the PWSA laboratory.
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Chapter 5
References
The following references were used in the preparation of this report:
American Public Health Association, American Water Works Association, Water
Environment Federation. Standard Methods for the Examination of Water and
Wastewater, APHA. AWWA, WEF, 18th Ed., 1992.
Gilbert, Richard O., Statistical Methods for Environmental Pollution Monitoring, Van
Nostrand Rheinhold, 1987.
Pall Corporation - Operations & Maintenance Manual - WPM - 1 Pilot System, Pall
Corp., February, 1998.
Pittsburgh Water and Sewer Authority. Laboratory Quality Assurance Plan, Non
Published, January, 1997.
U.S. Environmental Protection Agency. Enhanced Surface Water Treatment Rule
(ESWTR) - 40 CFR Parts 9, 141 and 142, EPA, February 16, 1999.
U.S. Environmental Protection Agency. Information Collection Rule (ICR) Microbial
Laboratory Manual, EPA, April 1996.
U.S. Environmental Protection Agency. Methods for Chemical Analysis of Water and
Wastes, EPA 600/479-020, March, 1979
U.S. Environmental Protection Agency. Optimizing Water Treatment Plant Performance
Using the Composite Correction Program. EPA/625/6-91/027, EPA1991b.
U.S. Environmental Protection Agency. Surface Water Treatment Rule (SWTR) - 54 FR
27486 June 29, 1989, EPA1989b.
U.S. Environmental Protection Agency /NSF International. ETV Protocol for Equipment
Verification Testing for Physical Removal of Microbiological and Particulate
Contamination, EPA/NSF, April, 1998.
U.S. Environmental Protection Agency /NSF International. ETV Protocol for Equipment
Verification Testing for Physical Removal of Microbiological and Particulate
Contamination, EPA/NSF, February, 1999.
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